diff --git a/miplearn/features/sample.py b/miplearn/features/sample.py
index 40b15af..e119500 100644
--- a/miplearn/features/sample.py
+++ b/miplearn/features/sample.py
@@ -35,6 +35,14 @@ VectorList = Union[
 class Sample(ABC):
     """Abstract dictionary-like class that stores training data."""
 
+    @abstractmethod
+    def get_bytes(self, key: str) -> Optional[bytes]:
+        pass
+
+    @abstractmethod
+    def put_bytes(self, key: str, value: bytes) -> None:
+        pass
+
     @abstractmethod
     def get_scalar(self, key: str) -> Optional[Any]:
         pass
@@ -101,6 +109,10 @@ class MemorySample(Sample):
             data = {}
         self._data: Dict[str, Any] = data
 
+    @overrides
+    def get_bytes(self, key: str) -> Optional[bytes]:
+        return self._get(key)
+
     @overrides
     def get_scalar(self, key: str) -> Optional[Any]:
         return self._get(key)
@@ -113,6 +125,11 @@ class MemorySample(Sample):
     def get_vector_list(self, key: str) -> Optional[Any]:
         return self._get(key)
 
+    @overrides
+    def put_bytes(self, key: str, value: bytes) -> None:
+        assert isinstance(value, bytes)
+        self._put(key, value)
+
     @overrides
     def put_scalar(self, key: str, value: Scalar) -> None:
         self._assert_is_scalar(value)
@@ -151,6 +168,12 @@ class Hdf5Sample(Sample):
     def __init__(self, filename: str) -> None:
         self.file = h5py.File(filename, "r+")
 
+    @overrides
+    def get_bytes(self, key: str) -> Optional[bytes]:
+        ds = self.file[key]
+        assert len(ds.shape) == 1
+        return ds[()].tobytes()
+
     @overrides
     def get_scalar(self, key: str) -> Optional[Any]:
         ds = self.file[key]
@@ -180,6 +203,11 @@ class Hdf5Sample(Sample):
             padded = ds[:].tolist()
         return _crop(padded, lens)
 
+    @overrides
+    def put_bytes(self, key: str, value: bytes) -> None:
+        assert isinstance(value, bytes)
+        self._put(key, np.frombuffer(value, dtype="uint8"))
+
     @overrides
     def put_scalar(self, key: str, value: Any) -> None:
         self._assert_is_scalar(value)
diff --git a/tests/features/test_sample.py b/tests/features/test_sample.py
index 5462210..f18ef1a 100644
--- a/tests/features/test_sample.py
+++ b/tests/features/test_sample.py
@@ -35,6 +35,17 @@ def _test_sample(sample: Sample) -> None:
     _assert_roundtrip_vector_list(sample, [[1], None, [2, 2], [3, 3, 3]])
     _assert_roundtrip_vector_list(sample, [[1.0], None, [2.0, 2.0], [3.0, 3.0, 3.0]])
 
+    # Bytes
+    _assert_roundtrip_bytes(sample, b"\x00\x01\x02\x03\x04\x05")
+
+
+def _assert_roundtrip_bytes(sample: Sample, expected: Any) -> None:
+    sample.put_bytes("key", expected)
+    actual = sample.get_bytes("key")
+    assert actual == expected
+    assert actual is not None
+    _assert_same_type(actual, expected)
+
 
 def _assert_roundtrip_scalar(sample: Sample, expected: Any) -> None:
     sample.put_scalar("key", expected)