diff --git a/app.py b/app.py
index 25a298d..833d84a 100644
--- a/app.py
+++ b/app.py
@@ -575,35 +575,62 @@ def api_content_timestamp():
         return jsonify({'error': 'Failed to get content timestamp'}), 500
 
 
+def build_comment_tree(comments):
+    """Build a hierarchical comment tree from flat comment list"""
+    # Create lookup dict by UUID
+    comment_dict = {c['uuid']: {**c, 'replies': []} for c in comments}
+
+    # Build tree structure
+    root_comments = []
+    for comment in comments:
+        parent_uuid = comment.get('parent_comment_uuid')
+        if parent_uuid and parent_uuid in comment_dict:
+            # Add as reply to parent
+            comment_dict[parent_uuid]['replies'].append(comment_dict[comment['uuid']])
+        else:
+            # Top-level comment
+            root_comments.append(comment_dict[comment['uuid']])
+
+    # Sort at each level by timestamp
+    def sort_tree(comments_list):
+        comments_list.sort(key=lambda x: x.get('timestamp', 0))
+        for comment in comments_list:
+            if comment.get('replies'):
+                sort_tree(comment['replies'])
+
+    sort_tree(root_comments)
+    return root_comments
+
+
 @app.route('/post/<post_id>')
 def post_detail(post_id):
     """Serve individual post detail page with modern theme"""
     try:
         # Load platform configuration
         platform_config = load_platform_config()
-        
+
         # Use cached data for better performance
         cached_posts, cached_comments = _load_posts_cache()
-        
+
         # Get post data from cache
         post_data = cached_posts.get(post_id)
         if not post_data:
             return render_template('404.html'), 404
-            
+
         # Add source display name
         post_data['source_display'] = get_display_name_for_source(
             post_data.get('platform', ''),
             post_data.get('source', ''),
             platform_config
         )
-            
-        # Get comments from cache
-        comments = cached_comments.get(post_id, [])
-        logger.info(f"Loading post {post_id}: found {len(comments)} comments")
 
-        # Sort comments by timestamp
-        comments.sort(key=lambda x: x.get('timestamp', 0))
-        
+        # Get comments from cache
+        comments_flat = cached_comments.get(post_id, [])
+        logger.info(f"Loading post {post_id}: found {len(comments_flat)} comments")
+
+        # Build comment tree
+        comments = build_comment_tree(comments_flat)
+
         # Load user settings if authenticated
         user_settings = {}
         if current_user.is_authenticated:
@@ -611,9 +638,9 @@ def post_detail(post_id):
                 user_settings = json.loads(current_user.settings) if current_user.settings else {}
             except:
                 user_settings = {}
-        
+
         return render_template('post_detail.html', post=post_data, comments=comments, user_settings=user_settings)
-        
+
     except Exception as e:
         print(f"Error loading post {post_id}: {e}")
         return render_template('404.html'), 404
diff --git a/templates/post_detail.html b/templates/post_detail.html
index c83bb02..0b8e714 100644
--- a/templates/post_detail.html
+++ b/templates/post_detail.html
@@ -135,25 +135,37 @@
     <!-- Comments Section -->
     <section class="comments-section">
         <h2>Comments ({{ comments|length }})</h2>
-        
+
+        {% macro render_comment(comment, depth=0) %}
+            <div class="comment" style="margin-left: {{ depth * 24 }}px;">
+                <div class="comment-header">
+                    <span class="comment-author">{{ comment.author }}</span>
+                    <span class="comment-separator">•</span>
+                    <span class="comment-time">{{ moment(comment.timestamp).fromNow() if moment else 'Recently' }}</span>
+                </div>
+                <div class="comment-content">
+                    {{ comment.content | safe | nl2br }}
+                </div>
+                <div class="comment-footer">
+                    <div class="comment-score">
+                        <span>▲ {{ comment.score or 0 }}</span>
+                    </div>
+                </div>
+
+                {% if comment.replies %}
+                    <div class="comment-replies">
+                        {% for reply in comment.replies %}
+                            {{ render_comment(reply, depth + 1) }}
+                        {% endfor %}
+                    </div>
+                {% endif %}
+            </div>
+        {% endmacro %}
+
         {% if comments %}
             <div class="comments-list">
                 {% for comment in comments %}
-                    <div class="comment">
-                        <div class="comment-header">
-                            <span class="comment-author">{{ comment.author }}</span>
-                            <span class="comment-separator">•</span>
-                            <span class="comment-time">{{ moment(comment.timestamp).fromNow() if moment else 'Recently' }}</span>
-                        </div>
-                        <div class="comment-content">
-                            {{ comment.content | safe | nl2br }}
-                        </div>
-                        <div class="comment-footer">
-                            <div class="comment-score">
-                                <span>▲ {{ comment.score or 0 }}</span>
-                            </div>
-                        </div>
-                    </div>
+                    {{ render_comment(comment) }}
                 {% endfor %}
             </div>
         {% else %}
@@ -554,12 +566,24 @@
 .comment {
     padding: 20px 0;
     border-bottom: 1px solid #f1f5f9;
+    position: relative;
 }
 
 .comment:last-child {
     border-bottom: none;
 }
 
+/* Threaded comment styling */
+.comment[style*="margin-left"] {
+    padding-left: 16px;
+    border-left: 2px solid #e2e8f0;
+    border-bottom: none;
+}
+
+.comment-replies {
+    margin-top: 8px;
+}
+
 .comment-header {
     display: flex;
     align-items: center;