diff --git a/app/controllers/groups_controller.rb b/app/controllers/groups_controller.rb
index 2dbcd8a..0cd4055 100644
--- a/app/controllers/groups_controller.rb
+++ b/app/controllers/groups_controller.rb
@@ -26,9 +26,10 @@ class GroupsController < ApplicationController
 
   def index
     @groups = Group.sorted.all
-
     respond_to do |format|
-      format.html
+      format.html {
+        @user_count_by_group_id = user_count_by_group_id
+      }
       format.api
     end
   end
@@ -138,4 +139,12 @@ class GroupsController < ApplicationController
   rescue ActiveRecord::RecordNotFound
     render_404
   end
+
+  def user_count_by_group_id
+    h = User.joins(:groups).group('group_id').count
+    h.keys.each do |key|
+      h[key.to_i] = h.delete(key)
+    end
+    h
+  end
 end
diff --git a/app/views/groups/index.html.erb b/app/views/groups/index.html.erb
index d48afe9..22c89ef 100644
--- a/app/views/groups/index.html.erb
+++ b/app/views/groups/index.html.erb
@@ -3,7 +3,6 @@
 </div>
 
 <%= title l(:label_group_plural) %>
-
 <% if @groups.any? %>
 <table class="list groups">
   <thead><tr>
@@ -13,9 +12,9 @@
   </tr></thead>
   <tbody>
 <% @groups.each do |group| %>
-  <tr class="<%= cycle 'odd', 'even' %>">
+  <tr id="group-<%= group.id %>" class="<%= cycle 'odd', 'even' %>">
     <td class="name"><%= link_to h(group), edit_group_path(group) %></td>
-    <td><%= group.users.size %></td>
+    <td class="user_count"><%= @user_count_by_group_id[group.id] || 0 %></td>
     <td class="buttons"><%= delete_link group %></td>
   </tr>
 <% end %>
diff --git a/test/functional/groups_controller_test.rb b/test/functional/groups_controller_test.rb
index 35f0a43..252472a 100644
--- a/test/functional/groups_controller_test.rb
+++ b/test/functional/groups_controller_test.rb
@@ -30,6 +30,12 @@ class GroupsControllerTest < ActionController::TestCase
     assert_template 'index'
   end
 
+  def test_index_should_show_user_count
+    get :index
+    assert_response :success
+    assert_select 'tr#group-11 td.user_count', :text => '1'
+  end
+
   def test_show
     get :show, :id => 10
     assert_response :success