diff --git a/docs/reqstream/review-mark/self-test/validation.yaml b/docs/reqstream/review-mark/self-test/validation.yaml
index 622ccd1..2c6641d 100644
--- a/docs/reqstream/review-mark/self-test/validation.yaml
+++ b/docs/reqstream/review-mark/self-test/validation.yaml
@@ -32,3 +32,4 @@ sections:
         tests:
           - Validation_Run_WithTrxResultsFile_WritesFile
           - Validation_Run_WithXmlResultsFile_WritesFile
+          - Validation_Run_WithResultsFileInNewDirectory_CreatesDirectory
diff --git a/src/DemaConsulting.ReviewMark/SelfTest/Validation.cs b/src/DemaConsulting.ReviewMark/SelfTest/Validation.cs
index 6fd8197..60f66ef 100644
--- a/src/DemaConsulting.ReviewMark/SelfTest/Validation.cs
+++ b/src/DemaConsulting.ReviewMark/SelfTest/Validation.cs
@@ -531,6 +531,12 @@ private static void WriteResultsFile(Context context, DemaConsulting.TestResults
                 return;
             }
 
+            var directory = Path.GetDirectoryName(context.ResultsFile);
+            if (!string.IsNullOrEmpty(directory))
+            {
+                Directory.CreateDirectory(directory);
+            }
+
             File.WriteAllText(context.ResultsFile, content);
             context.WriteLine($"Results written to {context.ResultsFile}");
         }
diff --git a/test/DemaConsulting.ReviewMark.Tests/SelfTest/ValidationTests.cs b/test/DemaConsulting.ReviewMark.Tests/SelfTest/ValidationTests.cs
index 1949dd6..3576944 100644
--- a/test/DemaConsulting.ReviewMark.Tests/SelfTest/ValidationTests.cs
+++ b/test/DemaConsulting.ReviewMark.Tests/SelfTest/ValidationTests.cs
@@ -202,4 +202,35 @@ public void Validation_Run_WithXmlResultsFile_WritesFile()
             }
         }
     }
+
+    /// <summary>
+    ///     Test that Run creates the parent directory when --results specifies a path with a non-existent parent.
+    /// </summary>
+    [TestMethod]
+    public void Validation_Run_WithResultsFileInNewDirectory_CreatesDirectory()
+    {
+        // Arrange — use TestDirectory as the root; the 'output' subdirectory does not exist yet
+        using var tempDir = new TestDirectory();
+        var subDir = Path.Combine(tempDir.DirectoryPath, "output");
+        var resultsFile = Path.Combine(subDir, "results.trx");
+
+        var originalOut = Console.Out;
+        try
+        {
+            using var outWriter = new StringWriter();
+            Console.SetOut(outWriter);
+            using var context = Context.Create(["--validate", "--results", resultsFile]);
+
+            // Act
+            Validation.Run(context);
+
+            // Assert — directory and results file were created
+            Assert.IsTrue(Directory.Exists(subDir), "Parent directory was not created");
+            Assert.IsTrue(File.Exists(resultsFile), "TRX results file was not created in new directory");
+        }
+        finally
+        {
+            Console.SetOut(originalOut);
+        }
+    }
 }