diff --git a/Govor.API.Tests/UnitTests/Services/UserGroupsServiceTests.cs b/Govor.API.Tests/UnitTests/Services/UserGroupsServiceTests.cs
new file mode 100644
index 0000000..4849ed8
--- /dev/null
+++ b/Govor.API.Tests/UnitTests/Services/UserGroupsServiceTests.cs
@@ -0,0 +1,70 @@
+using AutoFixture;
+using Govor.Application.Interfaces;
+using Govor.Application.Services;
+using Govor.Core.Models;
+using Govor.Core.Repositories.Groups;
+using Govor.Data.Repositories.Exceptions;
+using Moq;
+
+namespace Govor.API.Tests.UnitTests.Services;
+
+[TestFixture]
+public class UserGroupsServiceTests
+{
+    private Fixture _fixture;
+    private Mock<IGroupsRepository> _repositoryMock;
+    private IUserGroupsService _service;
+
+    [SetUp]
+    public void SetUp()
+    {
+        _fixture = new Fixture();
+
+        _fixture.Behaviors
+            .OfType<ThrowingRecursionBehavior>()
+            .ToList()
+            .ForEach(b => _fixture.Behaviors.Remove(b));
+
+        _fixture.Behaviors.Add(new OmitOnRecursionBehavior());
+        
+        _repositoryMock = new Mock<IGroupsRepository>();
+        
+        _service = new UserGroupsService(_repositoryMock.Object);
+    }
+
+    [Test]
+    public async Task GetUserGroups_ShouldReturnAllUserGroups()
+    {
+        // Arrange 
+        var chats = _fixture.CreateMany<ChatGroup>();
+        var userId = chats.First().Members.First().Id;
+
+        _repositoryMock.Setup(r => r.GetByUserIdAsync(userId))
+            .ReturnsAsync([chats.First()]);
+        
+        // Act 
+        var result = await _service.GetUserGroupsAsync(userId);
+        
+        // Assert 
+        Assert.That(result, Is.Not.Null);
+        Assert.That(result.Count(), Is.EqualTo(1));
+        Assert.That(result, Is.EquivalentTo([chats.First()]));
+    }
+    
+    [Test]
+    public async Task GetUserGroups_ButGroupDoesNotExist_ShouldReturnEmptyList()
+    {
+        // Arrange 
+        var userId = _fixture.Create<Guid>();
+        
+        _repositoryMock.Setup(r => r.GetByUserIdAsync(userId))
+            .ThrowsAsync(new NotFoundByKeyException<Guid>(userId));
+        
+        // Act 
+        var result = await _service.GetUserGroupsAsync(userId);
+        
+        // Assert 
+        Assert.That(result, Is.Not.Null);
+        Assert.That(result.Count(), Is.EqualTo(0));
+    }
+}
\ No newline at end of file
diff --git a/Govor.API/Extensions/ConfigurationProgramExtensions.cs b/Govor.API/Extensions/ConfigurationProgramExtensions.cs
index c727014..d9d49f8 100644
--- a/Govor.API/Extensions/ConfigurationProgramExtensions.cs
+++ b/Govor.API/Extensions/ConfigurationProgramExtensions.cs
@@ -52,6 +52,7 @@ public static class ConfigurationProgramExtensions
         
         services.AddScoped<IMessageService, MessageService>();
         services.AddScoped<IVerifyFriendship, VerifyFriendship>();
+        services.AddScoped<IUserGroupsService, UserGroupsService>();
     }
 
     public static void AddRepositories(this IServiceCollection services)
diff --git a/Govor.API/Hubs/ChatsHub.cs b/Govor.API/Hubs/ChatsHub.cs
index 8c5eb3e..792c7f4 100644
--- a/Govor.API/Hubs/ChatsHub.cs
+++ b/Govor.API/Hubs/ChatsHub.cs
@@ -1,4 +1,5 @@
 using Govor.API.Services;
+using Govor.Application.Interfaces;
 using Govor.Application.Interfaces.Messages;
 using Govor.Application.Interfaces.Messages.Parameters;
 using Govor.Contracts.Requests.SignalR;
@@ -14,6 +15,7 @@ public class ChatsHub : Hub
 {
     private readonly ILogger<ChatsHub> _logger;
     private readonly IMessageService _messageService;
+    private readonly IUserGroupsService _userService;
     
     public ChatsHub(ILogger<ChatsHub> logger, IMessageService messageService)
     {
@@ -34,13 +36,12 @@ public class ChatsHub : Hub
         // Add user to their own group (for private messages and notifications)
         await Groups.AddToGroupAsync(Context.ConnectionId, userId.ToString());
         _logger.LogInformation("User {UserId} connected with ConnectionId {ConnectionId} and added to their group", userId, Context.ConnectionId);
-
-        // TODO: Add user to their chat groups - this might require fetching user's groups from a service
-        // var userGroups = await _userService.GetUserGroupsAsync(userId);
-        // foreach (var group in userGroups)
-        // {
-        //     await Groups.AddToGroupAsync(Context.ConnectionId, $"group_{group.Id}");
-        // }
+        
+        var userGroups = await _userService.GetUserGroupsAsync(userId);
+        foreach (var group in userGroups)
+        {
+             await Groups.AddToGroupAsync(Context.ConnectionId, $"group_{group.Id}");
+        }
 
         await base.OnConnectedAsync();
     }
@@ -54,12 +55,12 @@ public class ChatsHub : Hub
             await Groups.RemoveFromGroupAsync(Context.ConnectionId, userId.ToString());
             _logger.LogInformation("User {UserId} disconnected with ConnectionId {ConnectionId} and removed from their group", userId, Context.ConnectionId);
 
-            // TODO: Remove user from their chat groups
-            // var userGroups = await _userService.GetUserGroupsAsync(userId); // This might be problematic if the service relies on the user being connected
-            // foreach (var group in userGroups)
-            // {
-            //     await Groups.RemoveFromGroupAsync(Context.ConnectionId, $"group_{group.Id}");
-            // }
+           
+            var userGroups = await _userService.GetUserGroupsAsync(userId); // This might be problematic if the service relies on the user being connected
+            foreach (var group in userGroups)
+            {
+                await Groups.RemoveFromGroupAsync(Context.ConnectionId, $"group_{group.Id}");
+            }
         }
         else if (exception != null)
         {
diff --git a/Govor.Application/Interfaces/IUserGroupsService.cs b/Govor.Application/Interfaces/IUserGroupsService.cs
new file mode 100644
index 0000000..1e51276
--- /dev/null
+++ b/Govor.Application/Interfaces/IUserGroupsService.cs
@@ -0,0 +1,8 @@
+using Govor.Core.Models;
+
+namespace Govor.Application.Interfaces;
+
+public interface IUserGroupsService
+{
+    Task<List<ChatGroup>> GetUserGroupsAsync(Guid userId);
+}
\ No newline at end of file
diff --git a/Govor.Application/Services/UserGroupsService.cs b/Govor.Application/Services/UserGroupsService.cs
new file mode 100644
index 0000000..04b04c0
--- /dev/null
+++ b/Govor.Application/Services/UserGroupsService.cs
@@ -0,0 +1,28 @@
+using Govor.Application.Interfaces;
+using Govor.Core.Models;
+using Govor.Core.Repositories.Groups;
+using Govor.Data.Repositories.Exceptions;
+
+namespace Govor.Application.Services;
+
+public class UserGroupsService : IUserGroupsService
+{
+    private readonly IGroupsRepository _groupRep;
+    
+    public UserGroupsService(IGroupsRepository groupsRepository)
+    {
+        _groupRep = groupsRepository;
+    }
+    
+    public async Task<List<ChatGroup>> GetUserGroupsAsync(Guid userId)
+    {
+        try
+        {
+            return await _groupRep.GetByUserIdAsync(userId);
+        }
+        catch (NotFoundByKeyException<Guid> ex)
+        {
+            return new List<ChatGroup>();
+        }
+    }
+}
\ No newline at end of file