diff --git a/news/531.bugfix b/news/531.bugfix
new file mode 100644
index 000000000..6c6e6339e
--- /dev/null
+++ b/news/531.bugfix
@@ -0,0 +1 @@
+Fix OmegaConf.to_yaml(cfg) when keys are of Enum type
diff --git a/omegaconf/basecontainer.py b/omegaconf/basecontainer.py
index 0a46cb5c8..40779037a 100644
--- a/omegaconf/basecontainer.py
+++ b/omegaconf/basecontainer.py
@@ -227,6 +227,8 @@ def convert(val: Node) -> Any:
                     )
 
                 assert node is not None
+                if enum_to_str and isinstance(key, Enum):
+                    key = f"{key.name}"
                 if isinstance(node, Container):
                     retdict[key] = BaseContainer._to_content(
                         node,
diff --git a/omegaconf/omegaconf.py b/omegaconf/omegaconf.py
index ee5b7c244..a79d7e76e 100644
--- a/omegaconf/omegaconf.py
+++ b/omegaconf/omegaconf.py
@@ -585,7 +585,7 @@ def to_container(
         Resursively converts an OmegaConf config to a primitive container (dict or list).
         :param cfg: the config to convert
         :param resolve: True to resolve all values
-        :param enum_to_str: True to convert Enum values to strings
+        :param enum_to_str: True to convert Enum keys and values to strings
         :param exclude_structured_configs: If True, do not convert Structured Configs
                (DictConfigs backed by a dataclass)
         :return: A dict or a list representing this config as a primitive container.
diff --git a/tests/test_to_container.py b/tests/test_to_container.py
index 48c92cb58..9854ab1fd 100644
--- a/tests/test_to_container.py
+++ b/tests/test_to_container.py
@@ -1,25 +1,25 @@
 import re
 from enum import Enum
-from typing import Any
+from typing import Any, Dict, List
 
-import pytest
+from pytest import mark, param, raises
 
 from omegaconf import DictConfig, ListConfig, OmegaConf
 from tests import Color, User
 
 
-@pytest.mark.parametrize(
+@mark.parametrize(
     "input_",
     [
-        pytest.param([1, 2, 3], id="list"),
-        pytest.param([1, 2, {"a": 3}], id="dict_in_list"),
-        pytest.param([1, 2, [10, 20]], id="list_in_list"),
-        pytest.param({"b": {"b": 10}}, id="dict_in_dict"),
-        pytest.param({"b": [False, 1, "2", 3.0, Color.RED]}, id="list_in_dict"),
-        pytest.param({"b": DictConfig(content=None)}, id="none_dictconfig"),
-        pytest.param({"b": ListConfig(content=None)}, id="none_listconfig"),
-        pytest.param({"b": DictConfig(content="???")}, id="missing_dictconfig"),
-        pytest.param({"b": ListConfig(content="???")}, id="missing_listconfig"),
+        param([1, 2, 3], id="list"),
+        param([1, 2, {"a": 3}], id="dict_in_list"),
+        param([1, 2, [10, 20]], id="list_in_list"),
+        param({"b": {"b": 10}}, id="dict_in_dict"),
+        param({"b": [False, 1, "2", 3.0, Color.RED]}, id="list_in_dict"),
+        param({"b": DictConfig(content=None)}, id="none_dictconfig"),
+        param({"b": ListConfig(content=None)}, id="none_listconfig"),
+        param({"b": DictConfig(content="???")}, id="missing_dictconfig"),
+        param({"b": ListConfig(content="???")}, id="missing_listconfig"),
     ],
 )
 def test_to_container_returns_primitives(input_: Any) -> None:
@@ -38,20 +38,20 @@ def assert_container_with_primitives(item: Any) -> None:
     assert_container_with_primitives(res)
 
 
-@pytest.mark.parametrize(
+@mark.parametrize(
     "cfg,ex_false,ex_true",
     [
-        pytest.param(
+        param(
             {"user": User(age=7, name="Bond")},
             {"user": {"name": "Bond", "age": 7}},
             {"user": User(age=7, name="Bond")},
         ),
-        pytest.param(
+        param(
             [1, User(age=7, name="Bond")],
             [1, {"name": "Bond", "age": 7}],
             [1, User(age=7, name="Bond")],
         ),
-        pytest.param(
+        param(
             {"users": [User(age=1, name="a"), User(age=2, name="b")]},
             {"users": [{"age": 1, "name": "a"}, {"age": 2, "name": "b"}]},
             {"users": [User(age=1, name="a"), User(age=2, name="b")]},
@@ -67,56 +67,56 @@ def test_exclude_structured_configs(cfg: Any, ex_false: Any, ex_true: Any) -> No
     assert ret1 == ex_true
 
 
-@pytest.mark.parametrize(
+@mark.parametrize(
     "src, expected, expected_with_resolve",
     [
-        pytest.param([], None, None, id="empty_list"),
-        pytest.param([1, 2, 3], None, None, id="list"),
-        pytest.param([None], None, None, id="list_with_none"),
-        pytest.param([1, "${0}", 3], None, [1, 1, 3], id="list_with_inter"),
-        pytest.param({}, None, None, id="empty_dict"),
-        pytest.param({"foo": "bar"}, None, None, id="dict"),
-        pytest.param(
+        param([], None, None, id="empty_list"),
+        param([1, 2, 3], None, None, id="list"),
+        param([None], None, None, id="list_with_none"),
+        param([1, "${0}", 3], None, [1, 1, 3], id="list_with_inter"),
+        param({}, None, None, id="empty_dict"),
+        param({"foo": "bar"}, None, None, id="dict"),
+        param(
             {"foo": "${bar}", "bar": "zonk"},
             None,
             {"foo": "zonk", "bar": "zonk"},
             id="dict_with_inter",
         ),
-        pytest.param({"foo": None}, None, None, id="dict_with_none"),
-        pytest.param({"foo": "???"}, None, None, id="dict_missing_value"),
-        pytest.param({"foo": None}, None, None, id="dict_none_value"),
+        param({"foo": None}, None, None, id="dict_with_none"),
+        param({"foo": "???"}, None, None, id="dict_missing_value"),
+        param({"foo": None}, None, None, id="dict_none_value"),
         # containers
-        pytest.param(
+        param(
             {"foo": DictConfig(is_optional=True, content=None)},
             {"foo": None},
             None,
             id="dict_none_dictconfig",
         ),
-        pytest.param(
+        param(
             {"foo": DictConfig(content="???")},
             {"foo": "???"},
             None,
             id="dict_missing_dictconfig",
         ),
-        pytest.param(
+        param(
             {"foo": DictConfig(content="${bar}"), "bar": 10},
             {"foo": "${bar}", "bar": 10},
             {"foo": 10, "bar": 10},
             id="dict_inter_dictconfig",
         ),
-        pytest.param(
+        param(
             {"foo": ListConfig(content="???")},
             {"foo": "???"},
             None,
             id="dict_missing_listconfig",
         ),
-        pytest.param(
+        param(
             {"foo": ListConfig(is_optional=True, content=None)},
             {"foo": None},
             None,
             id="dict_none_listconfig",
         ),
-        pytest.param(
+        param(
             {"foo": ListConfig(content="${bar}"), "bar": 10},
             {"foo": "${bar}", "bar": 10},
             {"foo": 10, "bar": 10},
@@ -137,7 +137,7 @@ def test_to_container(src: Any, expected: Any, expected_with_resolve: Any) -> No
 
 
 def test_to_container_invalid_input() -> None:
-    with pytest.raises(
+    with raises(
         ValueError,
         match=re.escape("Input cfg is not an OmegaConf config object (dict)"),
     ):
@@ -153,11 +153,11 @@ def test_string_interpolation_with_readonly_parent() -> None:
     }
 
 
-@pytest.mark.parametrize(
+@mark.parametrize(
     "src,expected",
     [
-        pytest.param(DictConfig(content="${bar}"), "${bar}", id="DictConfig"),
-        pytest.param(
+        param(DictConfig(content="${bar}"), "${bar}", id="DictConfig"),
+        param(
             OmegaConf.create({"foo": DictConfig(content="${bar}")}),
             {"foo": "${bar}"},
             id="nested_DictConfig",
@@ -167,3 +167,49 @@ def test_string_interpolation_with_readonly_parent() -> None:
 def test_to_container_missing_inter_no_resolve(src: Any, expected: Any) -> None:
     res = OmegaConf.to_container(src, resolve=False)
     assert res == expected
+
+
+class TestEnumToStr:
+    """Test the `enum_to_str` argument to the `OmegaConf.to_container function`"""
+
+    @mark.parametrize(
+        "src,enum_to_str,expected",
+        [
+            param({Color.RED: "enum key"}, True, "RED", id="convert"),
+            param({Color.RED: "enum key"}, False, Color.RED, id="dont-convert"),
+        ],
+    )
+    def test_enum_to_str_for_keys(
+        self, src: Any, enum_to_str: bool, expected: Any
+    ) -> None:
+        cfg = OmegaConf.create(src)
+        container: Dict[Any, Any] = OmegaConf.to_container(cfg, enum_to_str=enum_to_str)  # type: ignore
+        assert container == {expected: "enum key"}
+
+    @mark.parametrize(
+        "src,enum_to_str,expected",
+        [
+            param({"enum val": Color.RED}, True, "RED", id="convert"),
+            param({"enum val": Color.RED}, False, Color.RED, id="dont-convert"),
+        ],
+    )
+    def test_enum_to_str_for_values(
+        self, src: Any, enum_to_str: bool, expected: Any
+    ) -> None:
+        cfg = OmegaConf.create(src)
+        container: Dict[Any, Any] = OmegaConf.to_container(cfg, enum_to_str=enum_to_str)  # type: ignore
+        assert container == {"enum val": expected}
+
+    @mark.parametrize(
+        "src,enum_to_str,expected",
+        [
+            param([Color.RED], True, "RED", id="convert"),
+            param([Color.RED], False, Color.RED, id="dont-convert"),
+        ],
+    )
+    def test_enum_to_str_for_list(
+        self, src: Any, enum_to_str: bool, expected: Any
+    ) -> None:
+        cfg = OmegaConf.create(src)
+        container: List[Any] = OmegaConf.to_container(cfg, enum_to_str=enum_to_str)  # type: ignore
+        assert container == [expected]
diff --git a/tests/test_to_yaml.py b/tests/test_to_yaml.py
index 8f88a891a..49ed1807c 100644
--- a/tests/test_to_yaml.py
+++ b/tests/test_to_yaml.py
@@ -126,6 +126,14 @@ def test_to_yaml_with_enum() -> None:
     )
 
 
+def test_to_yaml_with_enum_key() -> None:
+    cfg = OmegaConf.create({Enum1.FOO: "enum key"})
+    expected = """FOO: enum key
+"""
+    s = OmegaConf.to_yaml(cfg)
+    assert s == expected
+
+
 def test_pretty_deprecated() -> None:
     c = OmegaConf.create({"foo": "bar"})
     with pytest.warns(