diff --git a/src/nichepca/utils/__init__.py b/src/nichepca/utils/__init__.py
index b2d3d0b..2f2a155 100644
--- a/src/nichepca/utils/__init__.py
+++ b/src/nichepca/utils/__init__.py
@@ -1 +1 @@
-from ._helper import check_for_raw_counts, to_numpy, to_torch
+from ._helper import check_for_raw_counts, normalize_per_sample, to_numpy, to_torch
diff --git a/src/nichepca/utils/_helper.py b/src/nichepca/utils/_helper.py
index f1a63a5..7329874 100644
--- a/src/nichepca/utils/_helper.py
+++ b/src/nichepca/utils/_helper.py
@@ -4,6 +4,7 @@
 from warnings import warn
 
 import numpy as np
+import scanpy as sc
 import scipy.sparse as sp
 import torch
 
@@ -81,3 +82,32 @@ def check_for_raw_counts(adata: AnnData):
             UserWarning,
             stacklevel=1,
         )
+
+
+def normalize_per_sample(adata, sample_key, **kwargs):
+    """
+    Normalize the per-sample counts in the `adata` object based on the given `sample_key`.
+
+    Parameters
+    ----------
+        adata : AnnData
+            The annotated data object.
+        sample_key : str
+            The key in `adata.obs` that identifies distinct samples.
+        kwargs : dict, optional
+            Additional keyword arguments to be passed to `sc.pp.normalize_total`.
+
+    Returns
+    -------
+    None
+    """
+    if kwargs.get("target_sum", None) is not None:
+        # if target sum is provided, samples make no difference
+        sc.pp.normalize_total(adata, **kwargs)
+    else:
+        adata.X = adata.X.astype(np.float32)
+        for sample in adata.obs[sample_key].unique():
+            mask = adata.obs[sample_key] == sample
+            sub_ad = adata[mask].copy()
+            sc.pp.normalize_total(sub_ad, **kwargs)
+            adata.X[mask.values] = sub_ad.X
diff --git a/tests/test_utils.py b/tests/test_utils.py
index 93f8a7b..86b90e8 100644
--- a/tests/test_utils.py
+++ b/tests/test_utils.py
@@ -2,6 +2,7 @@
 
 import numpy as np
 import pytest
+import scanpy as sc
 import torch
 from utils import generate_dummy_adata
 
@@ -49,3 +50,38 @@ def test_check_for_raw_counts():
     # Check for the specific warning
     with pytest.warns(UserWarning):
         npc.utils.check_for_raw_counts(adata)
+
+
+def test_normalize_per_sample():
+    sample_key = "sample"
+
+    target_sum = 1e4
+
+    adata_1 = generate_dummy_adata()
+    npc.utils.normalize_per_sample(
+        adata_1, target_sum=target_sum, sample_key=sample_key
+    )
+
+    adata_2 = generate_dummy_adata()
+    sc.pp.normalize_total(adata_2, target_sum=target_sum)
+
+    assert np.all(adata_1.X.toarray() == adata_2.X.toarray())
+
+    # second test without fixed target sum
+    target_sum = None
+
+    adata_1 = generate_dummy_adata()
+    npc.utils.normalize_per_sample(
+        adata_1, target_sum=target_sum, sample_key=sample_key
+    )
+
+    adata_2 = generate_dummy_adata()
+    adata_2.X = adata_2.X.astype(np.float32).toarray()
+
+    for sample in adata_2.obs[sample_key].unique():
+        mask = adata_2.obs[sample_key] == sample
+        sub_ad = adata_2[mask].copy()
+        sc.pp.normalize_total(sub_ad)
+        adata_2.X[mask.values] = sub_ad.X
+
+    assert np.all(adata_1.X.astype(np.float32).toarray() == adata_2.X)