diff --git a/data_structures/arrays/monotonic_array.py b/data_structures/arrays/monotonic_array.py
new file mode 100644
index 000000000..c50a21530
--- /dev/null
+++ b/data_structures/arrays/monotonic_array.py
@@ -0,0 +1,23 @@
+# https://leetcode.com/problems/monotonic-array/
+def is_monotonic(nums: list[int]) -> bool:
+    """
+    Check if a list is monotonic.
+
+    >>> is_monotonic([1, 2, 2, 3])
+    True
+    >>> is_monotonic([6, 5, 4, 4])
+    True
+    >>> is_monotonic([1, 3, 2])
+    False
+    """
+    return all(nums[i] <= nums[i + 1] for i in range(len(nums) - 1)) or all(
+        nums[i] >= nums[i + 1] for i in range(len(nums) - 1)
+    )
+
+
+# Test the function with your examples
+if __name__ == "__main__":
+    # Test the function with your examples
+    print(is_monotonic([1, 2, 2, 3]))  # Output: True
+    print(is_monotonic([6, 5, 4, 4]))  # Output: True
+    print(is_monotonic([1, 3, 2]))  # Output: False