diff --git a/b2sdk/_internal/exception.py b/b2sdk/_internal/exception.py
index aef410f3..8851a99d 100644
--- a/b2sdk/_internal/exception.py
+++ b/b2sdk/_internal/exception.py
@@ -27,6 +27,14 @@
 logger = logging.getLogger(__name__)
 
 
+def _parse_retry_after_seconds(retry_after_seconds):
+    """Return Retry-After delay-seconds, ignoring HTTP-date and invalid forms."""
+    try:
+        return int(retry_after_seconds)
+    except (TypeError, ValueError):
+        return None
+
+
 class B2Error(Exception, metaclass=ABCMeta):
     def __init__(self, *args, **kwargs):
         """
@@ -433,6 +441,10 @@ class ServiceError(TransientErrorMixin, B2Error):
     Used for HTTP status codes 500 through 599.
     """
 
+    def __init__(self, *args, retry_after_seconds=None):
+        super().__init__(*args)
+        self.retry_after_seconds = _parse_retry_after_seconds(retry_after_seconds)
+
 
 class CapExceeded(B2Error):
     def __str__(self):
@@ -452,11 +464,7 @@ def __str__(self):
 class TooManyRequests(B2Error):
     def __init__(self, retry_after_seconds=None):
         super().__init__()
-
-        if retry_after_seconds is not None:
-            self.retry_after_seconds = int(retry_after_seconds)
-        else:
-            self.retry_after_seconds = None
+        self.retry_after_seconds = _parse_retry_after_seconds(retry_after_seconds)
 
     def __str__(self):
         return 'Too many requests'
@@ -753,5 +761,8 @@ def interpret_b2_error(
     elif status == 429:
         return TooManyRequests(retry_after_seconds=response_headers.get('retry-after'))
     elif 500 <= status < 600:
-        return ServiceError('%d %s %s' % (status, code, message))
+        return ServiceError(
+            '%d %s %s' % (status, code, message),
+            retry_after_seconds=response_headers.get('retry-after'),
+        )
     return UnknownError('%d %s %s' % (status, code, message))
diff --git a/changelog.d/606.fixed.md b/changelog.d/606.fixed.md
new file mode 100644
index 00000000..bd710ff3
--- /dev/null
+++ b/changelog.d/606.fixed.md
@@ -0,0 +1 @@
+Fixed honoring the Retry-After header on 5xx service errors.
diff --git a/test/unit/b2http/test_b2http.py b/test/unit/b2http/test_b2http.py
index ae91e6bf..6ae18269 100644
--- a/test/unit/b2http/test_b2http.py
+++ b/test/unit/b2http/test_b2http.py
@@ -332,6 +332,30 @@ def test_works_second_try_status(self, b2_http: B2Http, mock_time: MagicMock):
         b2_http.request(responses.GET, self.URL, {})
         mock_time.assert_called_once_with(1.0)
 
+    @responses.activate
+    def test_service_error_honors_retry_after(self, b2_http: B2Http, mock_time: MagicMock):
+        _mock_error_response(self.URL, status=503, headers={'Retry-After': '2'})
+        responses.get(self.URL)
+
+        b2_http.request(responses.GET, self.URL, {})
+
+        mock_time.assert_called_once_with(2)
+
+    @responses.activate
+    def test_service_error_ignores_http_date_retry_after(
+        self, b2_http: B2Http, mock_time: MagicMock
+    ):
+        _mock_error_response(
+            self.URL,
+            status=503,
+            headers={'Retry-After': 'Wed, 21 Oct 2015 07:28:00 GMT'},
+        )
+        responses.get(self.URL)
+
+        b2_http.request(responses.GET, self.URL, {})
+
+        mock_time.assert_called_once_with(1.0)
+
     @responses.activate
     def test_never_works(self, b2_http: B2Http, mock_time: MagicMock):
         _mock_error_response(self.URL, status=503)
diff --git a/test/unit/test_exception.py b/test/unit/test_exception.py
index 258e301a..f4f6e8c9 100644
--- a/test/unit/test_exception.py
+++ b/test/unit/test_exception.py
@@ -147,6 +147,15 @@ def test_too_many_requests_without_retry_after_header(self):
         error = self._check_one(TooManyRequests, 429, '', '', {})
         assert error.retry_after_seconds is None
 
+    def test_service_error_with_retry_after_header(self):
+        retry_after = 200
+        error = self._check_one(ServiceError, 503, '', '', {'retry-after': retry_after})
+        assert error.retry_after_seconds == retry_after
+
+    def test_service_error_without_retry_after_header(self):
+        error = self._check_one(ServiceError, 503, '', '', {})
+        assert error.retry_after_seconds is None
+
     @pytest.mark.apiver(
         from_ver=3
     )  # previous apivers throw this as well, but BucketIdNotFound is a different class in them