diff --git a/flang/lib/Lower/OpenACC.cpp b/flang/lib/Lower/OpenACC.cpp
--- a/flang/lib/Lower/OpenACC.cpp
+++ b/flang/lib/Lower/OpenACC.cpp
@@ -101,6 +101,31 @@
   }
 }
 
+static llvm::SmallVector<mlir::Value>
+genBoundsOpsFromBox(fir::FirOpBuilder &builder, mlir::Location loc,
+                    Fortran::lower::AbstractConverter &converter,
+                    Fortran::lower::SymbolRef sym, mlir::Value box, int rank) {
+  llvm::SmallVector<mlir::Value> bounds;
+  mlir::Type idxTy = builder.getIndexType();
+  fir::ExtendedValue dataExv = converter.getSymbolExtendedValue(sym);
+  mlir::Type boundTy = builder.getType<mlir::acc::DataBoundsType>();
+  mlir::Value one = builder.createIntegerConstant(loc, idxTy, 1);
+  assert(box.getType().isa<fir::BaseBoxType>() && "expect firbox or fir.class");
+  for (int dim = 0; dim < rank; ++dim) {
+    mlir::Value d = builder.createIntegerConstant(loc, idxTy, dim);
+    mlir::Value baseLb =
+        fir::factory::readLowerBound(builder, loc, dataExv, dim, one);
+    auto dimInfo =
+        builder.create<fir::BoxDimsOp>(loc, idxTy, idxTy, idxTy, box, d);
+    mlir::Value empty;
+    mlir::Value bound = builder.create<mlir::acc::DataBoundsOp>(
+        loc, boundTy, empty, empty, dimInfo.getExtent(),
+        dimInfo.getByteStride(), true, baseLb);
+    bounds.push_back(bound);
+  }
+  return bounds;
+}
+
 static llvm::SmallVector<mlir::Value>
 genBoundsOps(fir::FirOpBuilder &builder, mlir::Location loc,
              Fortran::lower::AbstractConverter &converter,
@@ -126,6 +151,15 @@
       mlir::Value baseLb =
           fir::factory::readLowerBound(builder, loc, dataExv, dimension, one);
       bool defaultLb = baseLb == one;
+      mlir::Value stride;
+      bool strideInBytes = false;
+      if (fir::getBase(dataExv).getType().isa<fir::BaseBoxType>()) {
+        mlir::Value d = builder.createIntegerConstant(loc, idxTy, dimension);
+        auto dimInfo = builder.create<fir::BoxDimsOp>(loc, idxTy, idxTy, idxTy,
+                                                      fir::getBase(dataExv), d);
+        stride = dimInfo.getByteStride();
+        strideInBytes = true;
+      }
 
       const auto &lower{std::get<0>(triplet->t)};
       if (lower) {
@@ -188,9 +222,8 @@
         if (lbound)
           extent = builder.create<mlir::arith::SubIOp>(loc, extent, lbound);
       }
-      mlir::Value empty;
       mlir::Value bound = builder.create<mlir::acc::DataBoundsOp>(
-          loc, boundTy, lbound, ubound, extent, empty, false, baseLb);
+          loc, boundTy, lbound, ubound, extent, stride, strideInBytes, baseLb);
       bounds.push_back(bound);
       ++dimension;
     }
@@ -209,9 +242,8 @@
 
   fir::FirOpBuilder &builder = converter.getFirOpBuilder();
 
-  auto createOpAndAddOperand = [&](Fortran::lower::SymbolRef sym,
-                                   llvm::StringRef name,
-                                   mlir::Location loc) -> Op {
+  auto getDataOperandBaseAddr = [&](Fortran::lower::SymbolRef sym,
+                                    mlir::Location loc) -> mlir::Value {
     mlir::Value symAddr = converter.getSymbolAddress(sym);
     // TODO: Might need revisiting to handle for non-shared clauses
     if (!symAddr) {
@@ -223,14 +255,33 @@
     if (!symAddr)
       llvm::report_fatal_error("could not retrieve symbol address");
 
-    if (symAddr.getType().isa<fir::BaseBoxType>())
-      TODO(loc, "data operand operation creation for box types");
-    Op op = builder.create<Op>(loc, symAddr.getType(), symAddr);
+    mlir::Type symTy = symAddr.getType();
+    if (auto refTy = symTy.dyn_cast<fir::ReferenceType>())
+      symTy = refTy.getEleTy();
+
+    if (auto boxTy =
+            fir::unwrapRefType(symAddr.getType()).dyn_cast<fir::BaseBoxType>())
+      if (!boxTy.getEleTy().isa<fir::SequenceType>())
+        TODO(loc, "pointer, allocatable and derived type box");
+
+    return symAddr;
+  };
+
+  auto createOpAndAddOperand = [&](mlir::Value baseAddr, llvm::StringRef name,
+                                   mlir::Location loc,
+                                   llvm::SmallVector<mlir::Value> &bounds) {
+    if (baseAddr.getType().isa<fir::BaseBoxType>())
+      baseAddr = builder.create<fir::BoxAddrOp>(loc, baseAddr);
+
+    Op op = builder.create<Op>(loc, baseAddr.getType(), baseAddr);
     op.setNameAttr(builder.getStringAttr(name));
     op.setStructured(structured);
     op.setDataClause(dataClause);
+    if (bounds.size() > 0)
+      op->insertOperands(1, bounds);
     op->setAttr(Op::getOperandSegmentSizeAttr(),
-                builder.getDenseI32ArrayAttr({1, 0, 0}));
+                builder.getDenseI32ArrayAttr(
+                    {1, 0, static_cast<int32_t>(bounds.size())}));
     dataOperands.push_back(op.getAccPtr());
     return op;
   };
@@ -263,12 +314,10 @@
                                           asFortran, name);
                   }
                   asFortran << ')';
-                  Op op = createOpAndAddOperand(*name.symbol, asFortran.str(),
-                                                operandLocation);
-                  op->insertOperands(1, bounds);
-                  op->setAttr(Op::getOperandSegmentSizeAttr(),
-                              builder.getDenseI32ArrayAttr(
-                                  {1, 0, static_cast<int32_t>(bounds.size())}));
+                  mlir::Value baseAddr =
+                      getDataOperandBaseAddr(*name.symbol, operandLocation);
+                  createOpAndAddOperand(baseAddr, asFortran.str(),
+                                        operandLocation, bounds);
                 } else if (Fortran::parser::Unwrap<
                                Fortran::parser::StructureComponent>(
                                designator)) {
@@ -279,8 +328,15 @@
                           &designator.u)}) {
                     const Fortran::parser::Name &name =
                         Fortran::parser::GetLastName(*dataRef);
-                    createOpAndAddOperand(*name.symbol, name.ToString(),
-                                          operandLocation);
+                    mlir::Value baseAddr =
+                        getDataOperandBaseAddr(*name.symbol, operandLocation);
+                    llvm::SmallVector<mlir::Value> bounds;
+                    if (baseAddr.getType().isa<fir::BaseBoxType>())
+                      bounds = genBoundsOpsFromBox(builder, operandLocation,
+                                                   converter, *name.symbol,
+                                                   baseAddr, (*expr).Rank());
+                    createOpAndAddOperand(baseAddr, name.ToString(),
+                                          operandLocation, bounds);
                   } else { // Unsupported
                     llvm::report_fatal_error(
                         "Unsupported type of OpenACC operand");
@@ -291,8 +347,11 @@
             [&](const Fortran::parser::Name &name) {
               mlir::Location operandLocation =
                   converter.genLocation(name.source);
-              createOpAndAddOperand(*name.symbol, name.ToString(),
-                                    operandLocation);
+              mlir::Value baseAddr =
+                  getDataOperandBaseAddr(*name.symbol, operandLocation);
+              llvm::SmallVector<mlir::Value> bounds;
+              createOpAndAddOperand(baseAddr, name.ToString(), operandLocation,
+                                    bounds);
             }},
         accObject.u);
   }
diff --git a/flang/test/Lower/OpenACC/acc-enter-data.f90 b/flang/test/Lower/OpenACC/acc-enter-data.f90
--- a/flang/test/Lower/OpenACC/acc-enter-data.f90
+++ b/flang/test/Lower/OpenACC/acc-enter-data.f90
@@ -219,3 +219,138 @@
 !CHECK: acc.enter_data dataOperands(%[[CREATE]] : !fir.ref<!fir.array<10xi32>>)
 
 end subroutine
+
+! Test lowering of assumed size arrays.
+subroutine acc_enter_data_assumed(a, b, n, m)
+  integer :: n, m
+  real :: a(:)
+  real :: b(10:)
+
+!CHECK-LABEL: func.func @_QPacc_enter_data_assumed(
+!CHECK-SAME: %[[A:.*]]: !fir.box<!fir.array<?xf32>> {fir.bindc_name = "a"}, %[[B:.*]]: !fir.box<!fir.array<?xf32>> {fir.bindc_name = "b"}, %[[N:.*]]: !fir.ref<i32> {fir.bindc_name = "n"}, %[[M:.*]]: !fir.ref<i32> {fir.bindc_name = "m"}) {
+
+!CHECK: %[[LB_C10:.*]] = arith.constant 10 : i64
+!CHECK: %[[LB_C10_IDX:.*]] = fir.convert %[[LB_C10]] : (i64) -> index
+
+  !$acc enter data create(a)
+!CHECK: %[[C1:.*]] = arith.constant 1 : index
+!CHECK: %[[C0:.*]] = arith.constant 0 : index
+!CHECK: %[[DIMS:.*]]:3 = fir.box_dims %[[A]], %[[C0]] : (!fir.box<!fir.array<?xf32>>, index) -> (index, index, index)
+!CHECK: %[[BOUND:.*]] = acc.bounds extent(%[[DIMS]]#1 : index) stride(%[[DIMS]]#2 : index) startIdx(%[[C1]] : index) {strideInBytes = true}
+!CHECK: %[[BOX_ADDR:.*]] = fir.box_addr %[[A]] : (!fir.box<!fir.array<?xf32>>) -> !fir.ref<!fir.array<?xf32>>
+!CHECK: %[[CREATE:.*]] = acc.create varPtr(%[[BOX_ADDR]] : !fir.ref<!fir.array<?xf32>>) bounds(%[[BOUND]]) -> !fir.ref<!fir.array<?xf32>> {name = "a", structured = false}
+!CHECK: acc.enter_data dataOperands(%[[CREATE]] : !fir.ref<!fir.array<?xf32>>)
+
+  !$acc enter data create(a(:))
+!CHECK: %[[ONE:.*]] = arith.constant 1 : index
+!CHECK: %[[C0:.*]] = arith.constant 0 : index
+!CHECK: %[[DIMS0:.*]]:3 = fir.box_dims %[[A]], %[[C0]] : (!fir.box<!fir.array<?xf32>>, index) -> (index, index, index)
+!CHECK: %[[C0:.*]] = arith.constant 0 : index
+!CHECK: %[[DIMS1:.*]]:3 = fir.box_dims %[[A]], %[[C0]] : (!fir.box<!fir.array<?xf32>>, index) -> (index, index, index)
+!CHECK: %[[BOUND:.*]] = acc.bounds extent(%[[DIMS1]]#1 : index) stride(%[[DIMS0]]#2 : index) startIdx(%[[ONE]] : index) {strideInBytes = true}
+!CHECK: %[[BOX_ADDR:.*]] = fir.box_addr %[[A]] : (!fir.box<!fir.array<?xf32>>) -> !fir.ref<!fir.array<?xf32>>
+!CHECK: %[[CREATE:.*]] = acc.create varPtr(%[[BOX_ADDR]] : !fir.ref<!fir.array<?xf32>>) bounds(%[[BOUND]]) -> !fir.ref<!fir.array<?xf32>> {name = "a(:)", structured = false}
+!CHECK: acc.enter_data dataOperands(%[[CREATE]] : !fir.ref<!fir.array<?xf32>>)
+
+  !$acc enter data create(a(2:))
+!CHECK: %[[SIDX:.*]] = arith.constant 1 : index
+!CHECK: %[[C0:.*]] = arith.constant 0 : index
+!CHECK: %[[DIMS0:.*]]:3 = fir.box_dims %[[A]], %[[C0]] : (!fir.box<!fir.array<?xf32>>, index) -> (index, index, index)
+!CHECK: %[[LB:.*]] = arith.constant 1 : index
+!CHECK: %[[C0:.*]] = arith.constant 0 : index
+!CHECK: %[[DIMS1:.*]]:3 = fir.box_dims %[[A]], %[[C0]] : (!fir.box<!fir.array<?xf32>>, index) -> (index, index, index)
+!CHECK: %[[EXT:.*]] = arith.subi %[[DIMS1]]#1, %[[LB]] : index
+!CHECK: %[[BOUND:.*]] = acc.bounds lowerbound(%[[LB]] : index) extent(%[[EXT]] : index) stride(%[[DIMS0]]#2 : index) startIdx(%[[SIDX]] : index) {strideInBytes = true}
+!CHECK: %[[BOX_ADDR:.*]] = fir.box_addr %[[A]] : (!fir.box<!fir.array<?xf32>>) -> !fir.ref<!fir.array<?xf32>>
+!CHECK: %[[CREATE:.*]] = acc.create varPtr(%[[BOX_ADDR]] : !fir.ref<!fir.array<?xf32>>) bounds(%[[BOUND]]) -> !fir.ref<!fir.array<?xf32>> {name = "a(2:)", structured = false}
+!CHECK: acc.enter_data dataOperands(%[[CREATE]] : !fir.ref<!fir.array<?xf32>>)
+
+  !$acc enter data create(a(:4))
+!CHECK: %[[ONE:.*]] = arith.constant 1 : index
+!CHECK: %[[C0:.*]] = arith.constant 0 : index
+!CHECK: %[[DIMS0:.*]]:3 = fir.box_dims %[[A]], %[[C0]] : (!fir.box<!fir.array<?xf32>>, index) -> (index, index, index)
+!CHECK: %[[UB:.*]] = arith.constant 3 : index
+!CHECK: %[[BOUND:.*]] = acc.bounds upperbound(%[[UB]] : index) stride(%[[DIMS0]]#2 : index) startIdx(%[[ONE]] : index) {strideInBytes = true}
+!CHECK: %[[BOX_ADDR:.*]] = fir.box_addr %[[A]] : (!fir.box<!fir.array<?xf32>>) -> !fir.ref<!fir.array<?xf32>>
+!CHECK: %[[CREATE:.*]] = acc.create varPtr(%[[BOX_ADDR]] : !fir.ref<!fir.array<?xf32>>) bounds(%[[BOUND]]) -> !fir.ref<!fir.array<?xf32>> {name = "a(:4)", structured = false}
+!CHECK: acc.enter_data dataOperands(%[[CREATE]] : !fir.ref<!fir.array<?xf32>>)
+
+  !$acc enter data create(a(6:10))
+!CHECK: %[[ONE:.*]] = arith.constant 1 : index
+!CHECK: %[[C0:.*]] = arith.constant 0 : index
+!CHECK: %[[DIMS0:.*]]:3 = fir.box_dims %[[A]], %[[C0]] : (!fir.box<!fir.array<?xf32>>, index) -> (index, index, index)
+!CHECK: %[[LB:.*]] = arith.constant 5 : index
+!CHECK: %[[UB:.*]] = arith.constant 9 : index
+!CHECK: %[[BOUND:.*]] = acc.bounds lowerbound(%[[LB]] : index) upperbound(%[[UB]] : index) stride(%[[DIMS0]]#2 : index) startIdx(%[[ONE]] : index) {strideInBytes = true}
+!CHECK: %[[BOX_ADDR:.*]] = fir.box_addr %[[A]] : (!fir.box<!fir.array<?xf32>>) -> !fir.ref<!fir.array<?xf32>>
+!CHECK: %[[CREATE:.*]] = acc.create varPtr(%[[BOX_ADDR]] : !fir.ref<!fir.array<?xf32>>) bounds(%[[BOUND]]) -> !fir.ref<!fir.array<?xf32>> {name = "a(6:10)", structured = false}
+!CHECK: acc.enter_data dataOperands(%[[CREATE]] : !fir.ref<!fir.array<?xf32>>)
+
+  !$acc enter data create(a(n:))
+!CHECK: %[[ONE:.*]] = arith.constant 1 : index
+!CHECK: %[[C0:.*]] = arith.constant 0 : index
+!CHECK: %[[DIMS0:.*]]:3 = fir.box_dims %[[A]], %[[C0]] : (!fir.box<!fir.array<?xf32>>, index) -> (index, index, index)
+!CHECK: %[[LOAD_N:.*]] = fir.load %[[N]] : !fir.ref<i32>
+!CHECK: %[[CONVERT_N:.*]] = fir.convert %[[LOAD_N]] : (i32) -> index
+!CHECK: %[[LB:.*]] = arith.subi %[[CONVERT_N]], %[[ONE]] : index
+!CHECK: %[[C0:.*]] = arith.constant 0 : index
+!CHECK: %[[DIMS:.*]]:3 = fir.box_dims %[[A]], %[[C0]] : (!fir.box<!fir.array<?xf32>>, index) -> (index, index, index)
+!CHECK: %[[EXT:.*]] = arith.subi %[[DIMS]]#1, %[[LB]] : index
+!CHECK: %[[BOUND:.*]] = acc.bounds lowerbound(%[[LB]] : index) extent(%[[EXT]] : index) stride(%[[DIMS0]]#2 : index) startIdx(%[[ONE]] : index) {strideInBytes = true}
+!CHECK: %[[BOX_ADDR:.*]] = fir.box_addr %[[A]] : (!fir.box<!fir.array<?xf32>>) -> !fir.ref<!fir.array<?xf32>>
+!CHECK: %[[CREATE:.*]] = acc.create varPtr(%[[BOX_ADDR]] : !fir.ref<!fir.array<?xf32>>) bounds(%[[BOUND]]) -> !fir.ref<!fir.array<?xf32>> {name = "a(n:)", structured = false}
+!CHECK: acc.enter_data dataOperands(%[[CREATE]] : !fir.ref<!fir.array<?xf32>>)
+
+  !$acc enter data create(a(:m))
+!CHECK: %[[ONE:.*]] = arith.constant 1 : index
+!CHECK: %[[C0:.*]] = arith.constant 0 : index
+!CHECK: %[[DIMS0:.*]]:3 = fir.box_dims %[[A]], %[[C0]] : (!fir.box<!fir.array<?xf32>>, index) -> (index, index, index)
+!CHECK: %[[LOAD_M:.*]] = fir.load %[[M]] : !fir.ref<i32>
+!CHECK: %[[CONVERT_M:.*]] = fir.convert %[[LOAD_M]] : (i32) -> index
+!CHECK: %[[UB:.*]] = arith.subi %[[CONVERT_M]], %[[ONE]] : index
+!CHECK: %[[BOUND:.*]] = acc.bounds upperbound(%[[UB]] : index) stride(%[[DIMS0]]#2 : index) startIdx(%[[ONE]] : index) {strideInBytes = true}
+!CHECK: %[[BOX_ADDR:.*]] = fir.box_addr %[[A]] : (!fir.box<!fir.array<?xf32>>) -> !fir.ref<!fir.array<?xf32>>
+!CHECK: %[[CREATE:.*]] = acc.create varPtr(%[[BOX_ADDR]] : !fir.ref<!fir.array<?xf32>>) bounds(%[[BOUND]]) -> !fir.ref<!fir.array<?xf32>> {name = "a(:m)", structured = false}
+!CHECK: acc.enter_data dataOperands(%[[CREATE]] : !fir.ref<!fir.array<?xf32>>)
+
+  !$acc enter data create(a(n:m))
+!CHECK: %[[ONE:.*]] = arith.constant 1 : index
+!CHECK: %[[C0:.*]] = arith.constant 0 : index
+!CHECK: %[[DIMS0:.*]]:3 = fir.box_dims %[[A]], %[[C0]] : (!fir.box<!fir.array<?xf32>>, index) -> (index, index, index)
+!CHECK: %[[LOAD_N:.*]] = fir.load %[[N]] : !fir.ref<i32>
+!CHECK: %[[CONVERT_N:.*]] = fir.convert %[[LOAD_N]] : (i32) -> index
+!CHECK: %[[LB:.*]] = arith.subi %[[CONVERT_N]], %[[ONE]] : index
+!CHECK: %[[LOAD_M:.*]] = fir.load %[[M]] : !fir.ref<i32>
+!CHECK: %[[CONVERT_M:.*]] = fir.convert %[[LOAD_M]] : (i32) -> index
+!CHECK: %[[UB:.*]] = arith.subi %[[CONVERT_M]], %[[ONE]] : index
+!CHECK: %[[BOUND:.*]] = acc.bounds lowerbound(%[[LB]] : index) upperbound(%[[UB]] : index) stride(%[[DIMS0]]#2 : index) startIdx(%[[ONE]] : index) {strideInBytes = true}
+!CHECK: %[[BOX_ADDR:.*]] = fir.box_addr %[[A]] : (!fir.box<!fir.array<?xf32>>) -> !fir.ref<!fir.array<?xf32>>
+!CHECK: %[[CREATE:.*]] = acc.create varPtr(%[[BOX_ADDR]] : !fir.ref<!fir.array<?xf32>>) bounds(%[[BOUND]]) -> !fir.ref<!fir.array<?xf32>> {name = "a(n:m)", structured = false}
+!CHECK: acc.enter_data dataOperands(%[[CREATE]] : !fir.ref<!fir.array<?xf32>>)
+
+  !$acc enter data create(b(:m))
+!CHECK: %[[C0:.*]] = arith.constant 0 : index
+!CHECK: %[[DIMS0:.*]]:3 = fir.box_dims %[[B]], %[[C0]] : (!fir.box<!fir.array<?xf32>>, index) -> (index, index, index)
+!CHECK: %[[LOAD_M:.*]] = fir.load %[[M]] : !fir.ref<i32>
+!CHECK: %[[CONVERT_M:.*]] = fir.convert %[[LOAD_M]] : (i32) -> index
+!CHECK: %[[UB:.*]] = arith.subi %[[CONVERT_M]], %[[LB_C10_IDX]] : index
+!CHECK: %[[BOUND:.*]] = acc.bounds upperbound(%[[UB]] : index) stride(%[[DIMS0]]#2 : index) startIdx(%[[LB_C10_IDX]] : index) {strideInBytes = true}
+!CHECK: %[[BOX_ADDR:.*]] = fir.box_addr %[[B]] : (!fir.box<!fir.array<?xf32>>) -> !fir.ref<!fir.array<?xf32>>
+!CHECK: %[[CREATE:.*]] = acc.create varPtr(%[[BOX_ADDR]] : !fir.ref<!fir.array<?xf32>>) bounds(%[[BOUND]]) -> !fir.ref<!fir.array<?xf32>> {name = "b(:m)", structured = false}
+!CHECK: acc.enter_data dataOperands(%[[CREATE]] : !fir.ref<!fir.array<?xf32>>)
+
+  !$acc enter data create(b)
+!CHECK: %[[C0:.*]] = arith.constant 0 : index
+!CHECK: %[[DIMS0:.*]]:3 = fir.box_dims %[[B]], %[[C0]] : (!fir.box<!fir.array<?xf32>>, index) -> (index, index, index)
+!CHECK: %[[BOUND:.*]] = acc.bounds   extent(%[[DIMS0]]#1 : index) stride(%[[DIMS0]]#2 : index) startIdx(%[[LB_C10_IDX]] : index) {strideInBytes = true}
+!CHECK: %[[BOX_ADDR:.*]] = fir.box_addr %[[B]] : (!fir.box<!fir.array<?xf32>>) -> !fir.ref<!fir.array<?xf32>>
+!CHECK: %[[CREATE:.*]] = acc.create varPtr(%[[BOX_ADDR]] : !fir.ref<!fir.array<?xf32>>) bounds(%[[BOUND]]) -> !fir.ref<!fir.array<?xf32>> {name = "b", structured = false}
+!CHECK: acc.enter_data dataOperands(%[[CREATE]] : !fir.ref<!fir.array<?xf32>>)
+
+end subroutine
+
+subroutine acc_enter_data_allocatable()
+  real, allocatable :: a(:)
+
+!$acc enter data create(a)
+end subroutine