diff --git a/alibi_detect/utils/visualize.py b/alibi_detect/utils/visualize.py
index de9a4e1b5..8c72b64bd 100644
--- a/alibi_detect/utils/visualize.py
+++ b/alibi_detect/utils/visualize.py
@@ -79,6 +79,7 @@ def plot_feature_outlier_image(od_preds: Dict,
     instance_ids = instance_ids[:n_instances]
 
     if outliers_only and n_instances == 0:
+        warnings.warn('No outliers found!', UserWarning, stacklevel=3)
         return
 
     n_cols = 2