diff --git a/masque/file/dxf.py b/masque/file/dxf.py
index 0c19b5a..301910d 100644
--- a/masque/file/dxf.py
+++ b/masque/file/dxf.py
@@ -300,12 +300,57 @@ def _read_block(block: ezdxf.layouts.BlockLayout | ezdxf.layouts.Modelspace) ->
                 )
 
             if 'column_count' in attr:
-                args['repetition'] = Grid(
-                    a_vector=(attr['column_spacing'], 0),
-                    b_vector=(0, attr['row_spacing']),
-                    a_count=attr['column_count'],
-                    b_count=attr['row_count'],
+                col_spacing = attr['column_spacing']
+                row_spacing = attr['row_spacing']
+                col_count = attr['column_count']
+                row_count = attr['row_count']
+                local_x = numpy.array((col_spacing, 0.0))
+                local_y = numpy.array((0.0, row_spacing))
+                inv_rot = rotation_matrix_2d(-rotation)
+
+                candidates = (
+                    (inv_rot @ local_x, inv_rot @ local_y, col_count, row_count),
+                    (inv_rot @ local_y, inv_rot @ local_x, row_count, col_count),
                     )
+                repetition = None
+                for a_vector, b_vector, a_count, b_count in candidates:
+                    rotated_a = rotation_matrix_2d(rotation) @ a_vector
+                    rotated_b = rotation_matrix_2d(rotation) @ b_vector
+                    if (numpy.isclose(rotated_a[1], 0, atol=1e-8)
+                            and numpy.isclose(rotated_b[0], 0, atol=1e-8)
+                            and numpy.isclose(rotated_a[0], col_spacing, atol=1e-8)
+                            and numpy.isclose(rotated_b[1], row_spacing, atol=1e-8)
+                            and a_count == col_count
+                            and b_count == row_count):
+                        repetition = Grid(
+                            a_vector=a_vector,
+                            b_vector=b_vector,
+                            a_count=a_count,
+                            b_count=b_count,
+                            )
+                        break
+                    if (numpy.isclose(rotated_a[0], 0, atol=1e-8)
+                            and numpy.isclose(rotated_b[1], 0, atol=1e-8)
+                            and numpy.isclose(rotated_b[0], col_spacing, atol=1e-8)
+                            and numpy.isclose(rotated_a[1], row_spacing, atol=1e-8)
+                            and b_count == col_count
+                            and a_count == row_count):
+                        repetition = Grid(
+                            a_vector=a_vector,
+                            b_vector=b_vector,
+                            a_count=a_count,
+                            b_count=b_count,
+                            )
+                        break
+
+                if repetition is None:
+                    repetition = Grid(
+                        a_vector=inv_rot @ local_x,
+                        b_vector=inv_rot @ local_y,
+                        a_count=col_count,
+                        b_count=row_count,
+                        )
+                args['repetition'] = repetition
             pat.ref(**args)
         else:
             logger.warning(f'Ignoring DXF element {element.dxftype()} (not implemented).')
diff --git a/masque/test/test_dxf.py b/masque/test/test_dxf.py
index 0c0a1a3..5b038c6 100644
--- a/masque/test/test_dxf.py
+++ b/masque/test/test_dxf.py
@@ -112,6 +112,38 @@ def test_dxf_manhattan_precision(tmp_path: Path):
     assert isinstance(ref.repetition, Grid), "Grid should be preserved for 90-degree rotation"
 
 
+def test_dxf_rotated_grid_roundtrip_preserves_basis_and_counts(tmp_path: Path):
+    lib = Library()
+    sub = Pattern()
+    sub.polygon("1", vertices=[[0, 0], [1, 0], [1, 1]])
+    lib["sub"] = sub
+
+    top = Pattern()
+    top.ref(
+        "sub",
+        offset=(0, 0),
+        rotation=numpy.pi / 2,
+        repetition=Grid(a_vector=(10, 0), a_count=3, b_vector=(0, 20), b_count=2),
+        )
+    lib["top"] = top
+
+    dxf_file = tmp_path / "rotated_grid.dxf"
+    dxf.writefile(lib, "top", dxf_file)
+
+    read_lib, _ = dxf.readfile(dxf_file)
+    read_top = read_lib.get("Model") or read_lib.get("top") or list(read_lib.values())[0]
+
+    target_name = next(k for k in read_top.refs if k.upper() == "SUB")
+    ref = read_top.refs[target_name][0]
+    assert isinstance(ref.repetition, Grid)
+    actual = ref.repetition.displacements
+    expected = Grid(a_vector=(10, 0), a_count=3, b_vector=(0, 20), b_count=2).displacements
+    assert_allclose(
+        actual[numpy.lexsort((actual[:, 1], actual[:, 0]))],
+        expected[numpy.lexsort((expected[:, 1], expected[:, 0]))],
+        )
+
+
 def test_dxf_read_legacy_polyline() -> None:
     doc = ezdxf.new()
     msp = doc.modelspace()