diff --git a/backend/src/schema/resolvers/posts.js b/backend/src/schema/resolvers/posts.js
index a9f02b76b..e9f430d07 100644
--- a/backend/src/schema/resolvers/posts.js
+++ b/backend/src/schema/resolvers/posts.js
@@ -146,10 +146,12 @@ export default {
       const transactionRes = await session.run(
         `
         MATCH (post:Post {id: $postId})
+        OPTIONAL MATCH (post)<-[:COMMENTS]-(comment:Comment)
         SET post.deleted        = TRUE
         SET post.image          = 'DELETED'
         SET post.content        = 'DELETED'
         SET post.contentExcerpt = 'DELETED'
+        SET comment.deleted     = TRUE
         RETURN post
       `,
         { postId: args.id },
diff --git a/backend/src/schema/resolvers/posts.spec.js b/backend/src/schema/resolvers/posts.spec.js
index 8e1612f1d..107a90727 100644
--- a/backend/src/schema/resolvers/posts.spec.js
+++ b/backend/src/schema/resolvers/posts.spec.js
@@ -417,6 +417,11 @@ describe('DeletePost', () => {
         content
         contentExcerpt
         image
+        comments {
+          deleted
+          content
+          contentExcerpt
+        }
       }
     }
   `
@@ -466,6 +471,7 @@ describe('DeletePost', () => {
             content: 'DELETED',
             contentExcerpt: 'DELETED',
             image: 'DELETED',
+            comments: [],
           },
         },
       }
@@ -474,7 +480,40 @@ describe('DeletePost', () => {
       )
     })
 
-    it.todo('marks all comments as deleted')
+    describe('if there are comments on the post', () => {
+      beforeEach(async () => {
+        await factory.create('Comment', {
+          postId: 'p4711',
+          content: 'to be deleted comment content',
+          contentExcerpt: 'to be deleted comment content',
+        })
+      })
+
+      it('marks the comments as deleted', async () => {
+        const expected = {
+          data: {
+            DeletePost: {
+              id: 'p4711',
+              deleted: true,
+              content: 'DELETED',
+              contentExcerpt: 'DELETED',
+              image: 'DELETED',
+              comments: [
+                {
+                  deleted: true,
+                  // Should we black out the comment content in the database, too?
+                  content: 'to be deleted comment content',
+                  contentExcerpt: 'to be deleted comment content',
+                },
+              ],
+            },
+          },
+        }
+        await expect(mutate({ mutation: deletePostMutation, variables })).resolves.toMatchObject(
+          expected,
+        )
+      })
+    })
   })
 })