diff --git a/cad_core/lines.py b/cad_core/lines.py
index 112eb70..8e7ebb8 100644
--- a/cad_core/lines.py
+++ b/cad_core/lines.py
@@ -152,6 +152,7 @@ def trim_segment_by_cutter(seg: Line, cutter: Line, end: str = "b", tol: float =
 __all__ = [
     "Point",
     "Line",
+    "is_parallel",
     "intersection_line_line",
     "extend_line_end_to_point",
     "extend_line_to_intersection",
diff --git a/tests/cad_core/test_is_parallel.py b/tests/cad_core/test_is_parallel.py
new file mode 100644
index 0000000..277ab29
--- /dev/null
+++ b/tests/cad_core/test_is_parallel.py
@@ -0,0 +1,21 @@
+from cad_core.lines import Line, Point, is_parallel
+
+def test_parallel_lines():
+    l1 = Line(Point(0, 0), Point(10, 0))
+    l2 = Line(Point(0, 10), Point(10, 10))
+    assert is_parallel(l1, l2) is True
+
+def test_non_parallel_lines():
+    l1 = Line(Point(0, 0), Point(10, 0))
+    l2 = Line(Point(0, 0), Point(0, 10))
+    assert is_parallel(l1, l2) is False
+
+def test_collinear_lines():
+    l1 = Line(Point(0, 0), Point(10, 0))
+    l2 = Line(Point(20, 0), Point(30, 0))
+    assert is_parallel(l1, l2) is True
+
+def test_nearly_parallel_lines():
+    l1 = Line(Point(0, 0), Point(1000, 0))
+    l2 = Line(Point(0, 1e-10), Point(1000, 1e-10))
+    assert is_parallel(l1, l2) is True