diff --git a/Program.cs b/Program.cs
index 07d5483..ea3106d 100644
--- a/Program.cs
+++ b/Program.cs
@@ -17,16 +17,16 @@ namespace ttrss_co_client
             var apiLevel = await ttrssClient.GetApiLevel();
             Console.WriteLine($"api level: {apiLevel}");
 
-            var feeds = await ttrssClient.GetFeeds(cat_id: -3);
-            Console.WriteLine($"{feeds.Count()} feed{(feeds.Count() == 1 ? "" : "s")} found");
-            var firstUnread = feeds.FirstOrDefault(f => f.unread > 0);
+            var cats = await ttrssClient.GetCategories(include_empty: true);
+            Console.WriteLine($"{cats.Count()} categor{(cats.Count() == 1 ? "y" : "ies")} found");
+            var firstUnread = cats.FirstOrDefault(f => f.unread > 0);
             if(firstUnread != null)
             {
                 Console.WriteLine($"first unread: {firstUnread.title} (id {firstUnread.id})");
             }
             else
             {
-                Console.WriteLine("no feeds unread.");
+                Console.WriteLine("no categories with feeds with unread articles.");
             }
 
             var loggedout = await ttrssClient.Logout();
diff --git a/ttrss/ApiClient.cs b/ttrss/ApiClient.cs
index 2feb4a1..ddb9ef1 100644
--- a/ttrss/ApiClient.cs
+++ b/ttrss/ApiClient.cs
@@ -120,10 +120,23 @@ namespace ttrss_co_client.ttrss
             var apiResult = JsonConvert.DeserializeObject<ttrss.messages.FeedsResponse>(response);
             return apiResult.content;
         }
-        public async Task GetCategories(bool unread_only, bool enable_nested, bool include_empty)
+        ///<param name="enable_nested">nested mode (return only top level)</param>
+        public async Task<IEnumerable<Category>> GetCategories(bool unread_only = false, bool enable_nested = false, bool include_empty = false)
         {
             assertInitialized();
-            throw new NotImplementedException();
+            
+            var json = JsonContent.Create(new
+            {
+                op = "getCategories",
+                sid = this.SessionId,
+                unread_only = unread_only,
+                enable_nested = enable_nested,
+                include_empty = include_empty
+            });
+            var response = await (await httpClient.PostAsync(BaseURI, json)).Content.ReadAsStringAsync();
+            var apiResult = JsonConvert.DeserializeObject<ttrss.messages.CategoriesResponse>(response);
+            return apiResult.content;
+
         }
         public enum VIEWMODE { All, Unread, Adaptive, Marked, Updated }
         public enum SORTORDER { Default, OldestFirst, NewestFirst }
diff --git a/ttrss/datastructures/Category.cs b/ttrss/datastructures/Category.cs
new file mode 100644
index 0000000..c1cc3ae
--- /dev/null
+++ b/ttrss/datastructures/Category.cs
@@ -0,0 +1,12 @@
+using System.Collections.Generic;
+
+namespace ttrss_co_client.ttrss.datastructures
+{
+    public class Category
+    {
+        public int id { get; set; }
+        public string title { get; set; }
+        public int unread { get; set; }
+        public int order_id { get; set; }
+    }
+}
\ No newline at end of file
diff --git a/ttrss/datastructures/Feed.cs b/ttrss/datastructures/Feed.cs
index db84388..61ae180 100644
--- a/ttrss/datastructures/Feed.cs
+++ b/ttrss/datastructures/Feed.cs
@@ -2,7 +2,6 @@ using System.Collections.Generic;
 
 namespace ttrss_co_client.ttrss.datastructures
 {
-    ///<summary>"Counter Information" - not sure what that is</summary>
     public class Feed
     {
         public int id { get; set; }
diff --git a/ttrss/messages/CategoriesResponse.cs b/ttrss/messages/CategoriesResponse.cs
new file mode 100644
index 0000000..b454e37
--- /dev/null
+++ b/ttrss/messages/CategoriesResponse.cs
@@ -0,0 +1,9 @@
+using ttrss_co_client.ttrss.datastructures;
+
+namespace ttrss_co_client.ttrss.messages
+{
+    public class CategoriesResponse : ApiResponse
+    {
+        public IEnumerable<Category> content { get; set; }
+    }
+}
\ No newline at end of file