diff --git a/src/spac/visualization.py b/src/spac/visualization.py
index ef46f7c5..e08bfaa4 100644
--- a/src/spac/visualization.py
+++ b/src/spac/visualization.py
@@ -704,7 +704,8 @@ def heatmap(adata, column, layer=None, **kwargs):
 def hierarchical_heatmap(adata, annotation, features=None, layer=None,
                          cluster_feature=False, cluster_annotations=False,
                          standard_scale=None, z_score="annotation",
-                         swap_axes=False, rotate_label=False, **kwargs):
+                         swap_axes=False, rotate_label=False, 
+                         show_counts=False, **kwargs):
 
     """
     Generates a hierarchical clustering heatmap and dendrogram.
@@ -745,6 +746,9 @@ def hierarchical_heatmap(adata, annotation, features=None, layer=None,
         axis (rows) and features are on the horizontal axis (columns).
         When set to True, features will be on the vertical axis and
         annotations on the horizontal axis. Default is False.
+    show_counts : bool, optional
+        If True, adds the amount of cells to each cluster in the heatmap. 
+        Default is False.
     rotate_label : bool, optional
         If True, rotate x-axis labels by 45 degrees. Default is False.
     **kwargs:
@@ -910,6 +914,31 @@ def hierarchical_heatmap(adata, annotation, features=None, layer=None,
         'col_linkage': dendro_col_data
     }
 
+    if show_counts:
+
+        # Add cell counts to labels
+        # Retrieve the number of cells in each group
+        cell_counts = labels.value_counts()
+        cell_counts = dict(cell_counts)
+
+        # Retrieve the cluster labels from the heatmap
+        cluster_labels = clustergrid.ax_heatmap.get_yticklabels()
+
+        # Append the cell number to each cluster
+        numbered_labels = []
+        for x in cluster_labels:
+            key = int(x.get_text())
+            value = cell_counts[key]
+            numbered_label = f'cluster {key}\n{value} cells'
+            numbered_labels.append(numbered_label)
+
+        # add updated labels with cell counts to the heatmap
+        clustergrid.ax_heatmap.set_yticklabels(numbered_labels)
+        plt.setp(clustergrid.ax_heatmap.get_yticklabels(), rotation=0)
+
+        # adjust so labels don't get cut off
+        clustergrid.ax_heatmap.figure.subplots_adjust(right=0.9, left=0.1)
+
     return mean_intensity, clustergrid, dendrogram_data
 
 
diff --git a/tests/test_visualization/test_hierarchical_heatmap.py b/tests/test_visualization/test_hierarchical_heatmap.py
index 4b2b4863..de320d89 100644
--- a/tests/test_visualization/test_hierarchical_heatmap.py
+++ b/tests/test_visualization/test_hierarchical_heatmap.py
@@ -118,6 +118,26 @@ def test_axes_switching(self):
             mean_intensity_swapped.shape
         )
 
+    def test_cell_count_labels(self):
+        '''This test confirms the cell count labels are correct'''
+        # Set up AnnData object with known cell counts (3 cells in 1 cluster)
+        X_data = pd.DataFrame(
+            {'gene1': [1, 2, 3], 'gene2': [1, 2, 3], 'gene3': [1, 2, 3]}
+        )
+        obs_data = pd.DataFrame({'cluster': [1, 1, 1]})
+        self.adata = anndata.AnnData(X=X_data, obs=obs_data)
+
+        # Use hierarchical_heatmap function on AnnData object and get y-axis labels
+        _, clustergrid, _ = hierarchical_heatmap(self.adata, annotation='cluster', show_counts=True)
+        actual_labels = []
+        for label in clustergrid.ax_heatmap.get_yticklabels():
+            actual_labels.append(label.get_text())
+
+        # Confirm actual labels are in the expected labels
+        # dendrogram order varies if multiple clusters
+        expected_labels = ['cluster 1\n3 cells']
+        self.assertIn(expected_labels[0], actual_labels)
+
 
 if __name__ == "__main__":
     unittest.main()