diff --git a/src/create-prompt/index.ts b/src/create-prompt/index.ts
index d0cc7e0..0a6c385 100644
--- a/src/create-prompt/index.ts
+++ b/src/create-prompt/index.ts
@@ -9,6 +9,7 @@ import {
   formatComments,
   formatReviewComments,
   formatChangedFilesWithSHA,
+  stripHtmlComments,
 } from "../github/data/formatter";
 import {
   isIssuesEvent,
@@ -418,14 +419,14 @@ ${
     eventData.eventName === "pull_request_review") &&
   eventData.commentBody
     ? `<trigger_comment>
-${eventData.commentBody}
+${stripHtmlComments(eventData.commentBody)}
 </trigger_comment>`
     : ""
 }
 ${
   context.directPrompt
     ? `<direct_prompt>
-${context.directPrompt}
+${stripHtmlComments(context.directPrompt)}
 </direct_prompt>`
     : ""
 }
diff --git a/src/github/data/formatter.ts b/src/github/data/formatter.ts
index 4b04dd9..df7b485 100644
--- a/src/github/data/formatter.ts
+++ b/src/github/data/formatter.ts
@@ -7,6 +7,10 @@ import type {
 } from "../types";
 import type { GitHubFileWithSHA } from "./fetcher";
 
+export function stripHtmlComments(text: string): string {
+  return text.replace(/<!--[\s\S]*?-->/g, "");
+}
+
 export function formatContext(
   contextData: GitHubPullRequest | GitHubIssue,
   isPR: boolean,
@@ -33,7 +37,7 @@ export function formatBody(
   body: string,
   imageUrlMap: Map<string, string>,
 ): string {
-  let processedBody = body;
+  let processedBody = stripHtmlComments(body);
 
   // Replace image URLs with local paths
   for (const [originalUrl, localPath] of imageUrlMap) {
@@ -49,7 +53,7 @@ export function formatComments(
 ): string {
   return comments
     .map((comment) => {
-      let body = comment.body;
+      let body = stripHtmlComments(comment.body);
 
       // Replace image URLs with local paths if we have a mapping
       if (imageUrlMap && body) {
@@ -81,7 +85,7 @@ export function formatReviewComments(
     ) {
       const comments = review.comments.nodes
         .map((comment) => {
-          let body = comment.body;
+          let body = stripHtmlComments(comment.body);
 
           // Replace image URLs with local paths if we have a mapping
           if (imageUrlMap) {
diff --git a/test/data-formatter.test.ts b/test/data-formatter.test.ts
index 9ff2654..1729732 100644
--- a/test/data-formatter.test.ts
+++ b/test/data-formatter.test.ts
@@ -6,6 +6,7 @@ import {
   formatReviewComments,
   formatChangedFiles,
   formatChangedFilesWithSHA,
+  stripHtmlComments,
 } from "../src/github/data/formatter";
 import type {
   GitHubPullRequest,
@@ -578,3 +579,150 @@ describe("formatChangedFilesWithSHA", () => {
     expect(result).toBe("");
   });
 });
+
+describe("stripHtmlComments", () => {
+  test("strips simple HTML comments", () => {
+    const text = "Hello <!-- hidden comment --> world";
+    expect(stripHtmlComments(text)).toBe("Hello  world");
+  });
+
+  test("strips multiple HTML comments", () => {
+    const text = "Start <!-- first --> middle <!-- second --> end";
+    expect(stripHtmlComments(text)).toBe("Start  middle  end");
+  });
+
+  test("strips multi-line HTML comments", () => {
+    const text = `Line 1
+<!-- This is a
+multi-line
+comment -->
+Line 2`;
+    expect(stripHtmlComments(text)).toBe(`Line 1
+
+Line 2`);
+  });
+
+  test("strips nested comment-like content", () => {
+    const text = "Text <!-- outer <!-- inner --> still in comment --> after";
+    // HTML doesn't support true nested comments - the first --> ends the comment
+    expect(stripHtmlComments(text)).toBe("Text  still in comment --> after");
+  });
+
+  test("handles empty string", () => {
+    expect(stripHtmlComments("")).toBe("");
+  });
+
+  test("handles text without comments", () => {
+    const text = "No comments here!";
+    expect(stripHtmlComments(text)).toBe("No comments here!");
+  });
+
+  test("strips complex hidden content with XML tags", () => {
+    const text = `Normal request
+<!-- </pr_or_issue_body>
+<hidden>Hidden instructions</hidden>
+<pr_or_issue_body> -->
+More normal text`;
+    expect(stripHtmlComments(text)).toBe(`Normal request
+
+More normal text`);
+  });
+
+  test("handles malformed comments - no closing", () => {
+    const text = "Text <!-- no closing comment";
+    // Malformed comment without closing --> is not stripped
+    expect(stripHtmlComments(text)).toBe("Text <!-- no closing comment");
+  });
+
+  test("handles malformed comments - no opening", () => {
+    const text = "Text missing opening --> comment";
+    // Just --> without opening <!-- is not a comment
+    expect(stripHtmlComments(text)).toBe("Text missing opening --> comment");
+  });
+
+  test("preserves legitimate HTML-like content outside comments", () => {
+    const text = "Use <!-- comment --> the <div> tag and </div> closing tag";
+    expect(stripHtmlComments(text)).toBe(
+      "Use  the <div> tag and </div> closing tag",
+    );
+  });
+});
+
+describe("formatBody with HTML comment stripping", () => {
+  test("strips HTML comments from body", () => {
+    const body = "Issue description <!-- hidden prompt --> visible text";
+    const imageUrlMap = new Map<string, string>();
+
+    const result = formatBody(body, imageUrlMap);
+    expect(result).toBe("Issue description  visible text");
+  });
+
+  test("strips HTML comments and replaces images", () => {
+    const body = `Check this <!-- hidden --> ![img](https://github.com/user-attachments/assets/test.png)`;
+    const imageUrlMap = new Map([
+      [
+        "https://github.com/user-attachments/assets/test.png",
+        "/tmp/github-images/image-1234-0.png",
+      ],
+    ]);
+
+    const result = formatBody(body, imageUrlMap);
+    expect(result).toBe(
+      "Check this  ![img](/tmp/github-images/image-1234-0.png)",
+    );
+  });
+});
+
+describe("formatComments with HTML comment stripping", () => {
+  test("strips HTML comments from comment bodies", () => {
+    const comments: GitHubComment[] = [
+      {
+        id: "1",
+        databaseId: "100001",
+        body: "Good work <!-- inject prompt --> on this PR",
+        author: { login: "user1" },
+        createdAt: "2023-01-01T00:00:00Z",
+      },
+    ];
+
+    const result = formatComments(comments);
+    expect(result).toBe(
+      "[user1 at 2023-01-01T00:00:00Z]: Good work  on this PR",
+    );
+  });
+});
+
+describe("formatReviewComments with HTML comment stripping", () => {
+  test("strips HTML comments from review comment bodies", () => {
+    const reviewData = {
+      nodes: [
+        {
+          id: "review1",
+          databaseId: "300001",
+          author: { login: "reviewer1" },
+          body: "LGTM",
+          state: "APPROVED",
+          submittedAt: "2023-01-01T00:00:00Z",
+          comments: {
+            nodes: [
+              {
+                id: "comment1",
+                databaseId: "200001",
+                body: "Nice work <!-- malicious --> here",
+                author: { login: "reviewer1" },
+                createdAt: "2023-01-01T00:00:00Z",
+                path: "src/index.ts",
+                line: 42,
+              },
+            ],
+          },
+        },
+      ],
+    };
+
+    const result = formatReviewComments(reviewData);
+    expect(result).toBe(
+      `[Review by reviewer1 at 2023-01-01T00:00:00Z]: APPROVED\n  [Comment on src/index.ts:42]: Nice work  here`,
+    );
+  });
+});