diff --git a/CHANGELOG.md b/CHANGELOG.md
index ecabe9b..947e8f9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,8 @@ Breaking changes
 - ICF metadata format version bumped to ensure long-term compatility between numpy 1.26.x
   and numpy >= 2. Existing ICFs will need to be recreated.
 
+- Add chunksize options to mkschema (issue:294)
+
 # 0.1.1 2024-06-19
 
 Maintenance release:
diff --git a/bio2zarr/cli.py b/bio2zarr/cli.py
index 0722521..e37bd76 100644
--- a/bio2zarr/cli.py
+++ b/bio2zarr/cli.py
@@ -338,12 +338,19 @@ def inspect(path, verbose):
 
 @click.command
 @icf_path
-def mkschema(icf_path):
+@variants_chunk_size
+@samples_chunk_size
+def mkschema(icf_path, variants_chunk_size, samples_chunk_size):
     """
     Generate a schema for zarr encoding
     """
     stream = click.get_text_stream("stdout")
-    vcf2zarr.mkschema(icf_path, stream)
+    vcf2zarr.mkschema(
+        icf_path,
+        stream,
+        variants_chunk_size=variants_chunk_size,
+        samples_chunk_size=samples_chunk_size,
+    )
 
 
 @click.command
diff --git a/bio2zarr/vcf2zarr/vcz.py b/bio2zarr/vcf2zarr/vcz.py
index b4b42bf..3094b23 100644
--- a/bio2zarr/vcf2zarr/vcz.py
+++ b/bio2zarr/vcf2zarr/vcz.py
@@ -1027,9 +1027,13 @@ def encode_all_partitions(
                 pwm.submit(self.encode_partition, partition_index)
 
 
-def mkschema(if_path, out):
+def mkschema(if_path, out, *, variants_chunk_size=None, samples_chunk_size=None):
     store = icf.IntermediateColumnarFormat(if_path)
-    spec = VcfZarrSchema.generate(store)
+    spec = VcfZarrSchema.generate(
+        store,
+        variants_chunk_size=variants_chunk_size,
+        samples_chunk_size=samples_chunk_size,
+    )
     out.write(spec.asjson())
 
 
diff --git a/tests/test_cli.py b/tests/test_cli.py
index 4508637..2ede6ee 100644
--- a/tests/test_cli.py
+++ b/tests/test_cli.py
@@ -461,7 +461,9 @@ def test_inspect(self, mocked, tmp_path):
     def test_mkschema(self, mocked, tmp_path):
         runner = ct.CliRunner(mix_stderr=False)
         result = runner.invoke(
-            cli.vcf2zarr_main, f"mkschema {tmp_path}", catch_exceptions=False
+            cli.vcf2zarr_main,
+            f"mkschema {tmp_path} --variants-chunk-size=3 " "--samples-chunk-size=4",
+            catch_exceptions=False,
         )
         assert result.exit_code == 0
         assert len(result.stdout) == 0
@@ -705,6 +707,25 @@ def test_explode(self, tmp_path):
         # Arbitrary check
         assert "CHROM" in result.stdout
 
+    def test_mkschema(self, tmp_path):
+        icf_path = tmp_path / "icf"
+        runner = ct.CliRunner(mix_stderr=False)
+        result = runner.invoke(
+            cli.vcf2zarr_main,
+            f"explode {self.vcf_path} {icf_path}",
+            catch_exceptions=False,
+        )
+        assert result.exit_code == 0
+        result = runner.invoke(
+            cli.vcf2zarr_main,
+            f"mkschema {icf_path} --variants-chunk-size=3 " "--samples-chunk-size=2",
+            catch_exceptions=False,
+        )
+        assert result.exit_code == 0
+        d = json.loads(result.stdout)
+        assert d["samples_chunk_size"] == 2
+        assert d["variants_chunk_size"] == 3
+
     def test_encode(self, tmp_path):
         icf_path = tmp_path / "icf"
         zarr_path = tmp_path / "zarr"
diff --git a/tests/test_vcz.py b/tests/test_vcz.py
index f4b1843..6787461 100644
--- a/tests/test_vcz.py
+++ b/tests/test_vcz.py
@@ -136,6 +136,35 @@ def test_bad_value(self, tmp_path, icf_path, dimension_separator):
             )
 
 
+class TestSchemaChunkSize:
+    @pytest.mark.parametrize(
+        ("samples_chunk_size", "variants_chunk_size"),
+        [
+            (1, 2),
+            (2, 1),
+            (3, 5),
+        ],
+    )
+    def test_chunk_sizes(self, icf_path, samples_chunk_size, variants_chunk_size):
+        icf = vcf2zarr.IntermediateColumnarFormat(icf_path)
+        schema = vcf2zarr.VcfZarrSchema.generate(
+            icf,
+            variants_chunk_size=variants_chunk_size,
+            samples_chunk_size=samples_chunk_size,
+        )
+        assert schema.samples_chunk_size == samples_chunk_size
+        assert schema.variants_chunk_size == variants_chunk_size
+        found = 0
+        for field in schema.fields:
+            assert field.dimensions[0] == "variants"
+            assert field.chunks[0] == variants_chunk_size
+            if "samples" in field.dimensions:
+                dim = field.dimensions.index("samples")
+                assert field.chunks[dim] == samples_chunk_size
+                found += 1
+        assert found > 0
+
+
 class TestSchemaJsonRoundTrip:
     def assert_json_round_trip(self, schema):
         schema2 = vcf2zarr.VcfZarrSchema.fromjson(schema.asjson())