diff --git a/src/GitHub.App/ViewModels/PullRequestReviewCommentThreadViewModel.cs b/src/GitHub.App/ViewModels/PullRequestReviewCommentThreadViewModel.cs
index f5ddb65bb6..3a6472778a 100644
--- a/src/GitHub.App/ViewModels/PullRequestReviewCommentThreadViewModel.cs
+++ b/src/GitHub.App/ViewModels/PullRequestReviewCommentThreadViewModel.cs
@@ -70,6 +70,9 @@ public IPullRequestSessionFile File
         /// <inheritdoc/>
         public DiffSide Side { get; private set; }
 
+        /// <inheritdoc/>
+        public bool IsOutdated { get; private set; }
+
         /// <inheritdoc/>
         public bool IsResolved { get; private set; }
 
@@ -101,6 +104,7 @@ public async Task InitializeAsync(
             LineNumber = thread.LineNumber;
             Side = thread.DiffLineType == DiffChangeType.Delete ? DiffSide.Left : DiffSide.Right;
             IsResolved = thread.IsResolved;
+            IsOutdated = thread.IsOutdated;
 
             foreach (var comment in thread.Comments)
             {
diff --git a/src/GitHub.Exports.Reactive/Models/IInlineCommentThreadModel.cs b/src/GitHub.Exports.Reactive/Models/IInlineCommentThreadModel.cs
index 802971c167..a4216ccd62 100644
--- a/src/GitHub.Exports.Reactive/Models/IInlineCommentThreadModel.cs
+++ b/src/GitHub.Exports.Reactive/Models/IInlineCommentThreadModel.cs
@@ -50,6 +50,11 @@ public interface IInlineCommentThreadModel
         /// </summary>
         string RelativePath { get; }
 
+        /// <summary>
+        /// Gets a value indicating whether the thread is outdated.
+        /// </summary>
+        bool IsOutdated { get; }
+
         /// <summary>
         /// Gets a value indicating whether comment thread has been marked as resolved by a user.
         /// </summary>
diff --git a/src/GitHub.Exports.Reactive/ViewModels/IPullRequestReviewCommentThreadViewModel.cs b/src/GitHub.Exports.Reactive/ViewModels/IPullRequestReviewCommentThreadViewModel.cs
index b669927a07..0b99a44f31 100644
--- a/src/GitHub.Exports.Reactive/ViewModels/IPullRequestReviewCommentThreadViewModel.cs
+++ b/src/GitHub.Exports.Reactive/ViewModels/IPullRequestReviewCommentThreadViewModel.cs
@@ -36,6 +36,11 @@ public interface IPullRequestReviewCommentThreadViewModel : ICommentThreadViewMo
         /// </summary>
         DiffSide Side { get; }
 
+        /// <summary>
+        /// Gets a value indicating whether the thread is outdated.
+        /// </summary>
+        bool IsOutdated { get; }
+
         /// <summary>
         /// Gets a value indicating whether comment thread has been marked as resolved by a user.
         /// </summary>
diff --git a/src/GitHub.InlineReviews/Models/InlineCommentThreadModel.cs b/src/GitHub.InlineReviews/Models/InlineCommentThreadModel.cs
index c47b0adf6f..9bbfea103a 100644
--- a/src/GitHub.InlineReviews/Models/InlineCommentThreadModel.cs
+++ b/src/GitHub.InlineReviews/Models/InlineCommentThreadModel.cs
@@ -29,6 +29,7 @@ public InlineCommentThreadModel(
             string commitSha,
             IList<DiffLine> diffMatch,
             IEnumerable<InlineCommentModel> comments,
+            bool isOutdated,
             bool isResolved)
         {
             Guard.ArgumentNotNull(relativePath, nameof(relativePath));
@@ -40,6 +41,7 @@ public InlineCommentThreadModel(
             DiffLineType = diffMatch[0].Type;
             CommitSha = commitSha;
             RelativePath = relativePath;
+            IsOutdated = isOutdated;
             IsResolved = isResolved;
 
             foreach (var comment in comments)
@@ -77,6 +79,9 @@ public int LineNumber
         /// <inheritdoc/>
         public string RelativePath { get; }
 
+        /// <inheritdoc/>
+        public bool IsOutdated { get; }
+
         /// <inheritdoc/>
         public bool IsResolved { get; }
     }
diff --git a/src/GitHub.InlineReviews/Services/PullRequestSessionService.cs b/src/GitHub.InlineReviews/Services/PullRequestSessionService.cs
index 871a62668b..c8864f7baf 100644
--- a/src/GitHub.InlineReviews/Services/PullRequestSessionService.cs
+++ b/src/GitHub.InlineReviews/Services/PullRequestSessionService.cs
@@ -145,6 +145,7 @@ public IReadOnlyList<IInlineCommentThreadModel> BuildCommentThreads(
                         Comment = c,
                         Review = pullRequest.Reviews.FirstOrDefault(x => x.Comments.Contains(c)),
                     })),
+                    reviewThread.IsOutdated,
                     reviewThread.IsResolved);
                 threads.Add(inlineThread);
             }
diff --git a/src/GitHub.InlineReviews/Views/InlineCommentPeekView.xaml b/src/GitHub.InlineReviews/Views/InlineCommentPeekView.xaml
index 0ca2f48b4c..ca1707e215 100644
--- a/src/GitHub.InlineReviews/Views/InlineCommentPeekView.xaml
+++ b/src/GitHub.InlineReviews/Views/InlineCommentPeekView.xaml
@@ -82,6 +82,25 @@
             </DockPanel>
         </Border>
 
+        <Border DockPanel.Dock="Top"
+                Background="{DynamicResource {x:Static SystemColors.InfoBrushKey}}"
+                Padding="8">
+            <Border.Style>
+                <Style TargetType="Border">
+                    <Setter Property="Visibility" Value="Collapsed"/>
+                    <Style.Triggers>
+                        <DataTrigger Binding="{Binding Thread.IsOutdated}" Value="True">
+                            <Setter Property="Visibility" Value="Visible"/>
+                        </DataTrigger>
+                    </Style.Triggers>
+                </Style>
+            </Border.Style>
+            <DockPanel>
+                <ui:OcticonImage DockPanel.Dock="Left" Icon="alert" Margin="0 0 8 0"/>
+                <TextBlock TextWrapping="Wrap" Text="{x:Static ghfvs:Resources.YouAreViewingAnOutdatedVersionOfThisFile}"/>
+            </DockPanel>
+        </Border>
+
         <Border DockPanel.Dock="Top"
                 BorderThickness="0 0 0 1"
                 Background="{DynamicResource VsBrush.CommandBarOptionsBackground}"
diff --git a/src/GitHub.Resources/Resources.Designer.cs b/src/GitHub.Resources/Resources.Designer.cs
index 7dcf2d1003..0b0ad10244 100644
--- a/src/GitHub.Resources/Resources.Designer.cs
+++ b/src/GitHub.Resources/Resources.Designer.cs
@@ -2324,6 +2324,15 @@ public static string years {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to You are viewing an outdated version of this file.
+        /// </summary>
+        public static string YouAreViewingAnOutdatedVersionOfThisFile {
+            get {
+                return ResourceManager.GetString("YouAreViewingAnOutdatedVersionOfThisFile", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to You have already cloned to this location. Click &apos;Open&apos; to open the local repository..
         /// </summary>
diff --git a/src/GitHub.Resources/Resources.resx b/src/GitHub.Resources/Resources.resx
index 84594d6ca8..9124f95e0f 100644
--- a/src/GitHub.Resources/Resources.resx
+++ b/src/GitHub.Resources/Resources.resx
@@ -884,4 +884,7 @@ https://git-scm.com/download/win</value>
   <data name="ThisConversationWasMarkedAsResolved" xml:space="preserve">
     <value>This conversation was marked as resolved</value>
   </data>
+  <data name="YouAreViewingAnOutdatedVersionOfThisFile" xml:space="preserve">
+    <value>You are viewing an outdated version of this file</value>
+  </data>
 </root>
\ No newline at end of file