diff --git a/docs/user_guide/storing/index_hnswlib.md b/docs/user_guide/storing/index_hnswlib.md
index d873c059a57..d8f5ee633e8 100644
--- a/docs/user_guide/storing/index_hnswlib.md
+++ b/docs/user_guide/storing/index_hnswlib.md
@@ -123,16 +123,19 @@ In the example above you can see how to configure two different vector fields, w
 
 In this way, you can pass [all options that Hnswlib supports](https://github.com/nmslib/hnswlib#api-description):
 
-| Keyword           | Description                                                                                                                    | Default |
-|-------------------|--------------------------------------------------------------------------------------------------------------------------------|---------|
-| `max_elements`    | Maximum number of vector that can be stored                                                                                    | 1024    |
-| `space`           | Vector space (similarity metric) the index operates in. Supports 'l2', 'ip', and 'cosine'                                      | 'l2'    |
-| `index`           | Whether or not an index should be built for this field.                                                                        | True    |
-| `ef_construction` | defines a construction time/accuracy trade-off | 200     |
-| `ef`              | parameter controlling query time/accuracy trade-off | 10      |
-| `M`               | parameter that defines the maximum number of outgoing connections in the graph | 16      |
-| `allow_replace_deleted`       | enables replacing of deleted elements with new added ones | True    |
-| `num_threads`  | sets the number of cpu threads to use | 1       |
+| Keyword           | Description                                                                                                                                                                                                                                                                                                                                                                                                                            | Default |
+|-------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------|
+| `max_elements`    | Maximum number of vector that can be stored                                                                                                                                                                                                                                                                                                                                                                                            | 1024    |
+| `space`           | Vector space (distance metric) the index operates in. Supports 'l2', 'ip', and 'cosine'. <br/><span style="color:black">**Note:** In contrast to the other backends, for HnswDocumentIndex `'cosine'` refers to **cosine distance**, not cosine similarity. To transform one to the other, you can use: `cos_sim = 1 - cos_dist`. For more details see [here](https://en.wikipedia.org/wiki/Cosine_similarity#Cosine_Distance)</span>. | 'l2'    |
+| `index`           | Whether or not an index should be built for this field.                                                                                                                                                                                                                                                                                                                                                                                | True    |
+| `ef_construction` | defines a construction time/accuracy trade-off                                                                                                                                                                                                                                                                                                                                                                                         | 200     |
+| `ef`              | parameter controlling query time/accuracy trade-off                                                                                                                                                                                                                                                                                                                                                                                    | 10      |
+| `M`               | parameter that defines the maximum number of outgoing connections in the graph                                                                                                                                                                                                                                                                                                                                                         | 16      |
+| `allow_replace_deleted`       | enables replacing of deleted elements with new added ones                                                                                                                                                                                                                                                                                                                                                                              | True    |
+| `num_threads`  | sets the number of cpu threads to use                                                                                                                                                                                                                                                                                                                                                                                                  | 1       |
+
+!!! note
+    In HnswLibDocIndex  `space='cosine'` refers to cosine distance, not to cosine similarity, as it does for the other backends. 
 
 You can find more details on the parameters [here](https://github.com/nmslib/hnswlib/blob/master/ALGO_PARAMS.md).