diff --git a/swh/model/identifiers.py b/swh/model/identifiers.py
--- a/swh/model/identifiers.py
+++ b/swh/model/identifiers.py
@@ -638,18 +638,35 @@
 
 
 PERSISTENT_IDENTIFIER_KEYS = [
-    'namespace', 'scheme_version', 'object_type', 'object_id']
+    'namespace', 'scheme_version', 'object_type', 'object_id', 'metadata']
+
+PERSISTENT_IDENTIFIER_PARTS_SEP = ';'
 
 
 def parse_persistent_identifier(persistent_id):
-    """Parse swh's persistent identifier scheme.
+    """Parse swh's :ref:`persistent-identifiers` scheme.
 
     Args:
         persistent_id (str): A persistent identifier
 
     Returns:
-        dict with keys namespace, scheme_version, object_type, object_id
+        dict: dict with keys :
+
+            * namespace, holding str value
+            * scheme_version, holding str value
+            * object_type, holding str value
+            * object_id, holding str value
+            * metadata, holding dict value
 
     """
-    data = persistent_id.split(':')
+    persistent_id_parts = persistent_id.split(PERSISTENT_IDENTIFIER_PARTS_SEP)
+    data = persistent_id_parts.pop(0).split(':')
+    persistent_id_metadata = {}
+    for part in persistent_id_parts:
+        try:
+            key, val = part.split('=')
+            persistent_id_metadata[key] = val
+        except Exception:
+            pass
+    data.append(persistent_id_metadata)
     return dict(zip(PERSISTENT_IDENTIFIER_KEYS, data))
diff --git a/swh/model/tests/test_identifiers.py b/swh/model/tests/test_identifiers.py
--- a/swh/model/tests/test_identifiers.py
+++ b/swh/model/tests/test_identifiers.py
@@ -818,6 +818,32 @@
                 'scheme_version': _version,
                 'object_type': _type,
                 'object_id': _hash,
+                'metadata': {}
+            }
+            actual_result = identifiers.parse_persistent_identifier(pid)
+            self.assertEquals(actual_result, expected_result)
+
+        for pid, _type, _version, _hash, _metadata in [
+                ('swh:1:cnt:9c95815d9e9d91b8dae8e05d8bbc696fe19f796b;lines=1-18;origin=https://github.com/python/cpython', # noqa
+                 'cnt', '1', '9c95815d9e9d91b8dae8e05d8bbc696fe19f796b',
+                 {
+                     'lines': '1-18',
+                     'origin': 'https://github.com/python/cpython'
+                 }),
+                 ('swh:1:dir:0b6959356d30f1a4e9b7f6bca59b9a336464c03d;origin=deb://Debian/packages/linuxdoc-tools', # noqa
+                  'dir', '1', '0b6959356d30f1a4e9b7f6bca59b9a336464c03d',
+                 {
+                     'origin': 'deb://Debian/packages/linuxdoc-tools'
+                 }),
+                 ('swh:1:dir:0b6959356d30f1a4e9b7f6bca59b9a336464c03d;invalid;malformed', # noqa
+                  'dir', '1', '0b6959356d30f1a4e9b7f6bca59b9a336464c03d', {})
+        ]:
+            expected_result = {
+                'namespace': 'swh',
+                'scheme_version': _version,
+                'object_type': _type,
+                'object_id': _hash,
+                'metadata': _metadata
             }
             actual_result = identifiers.parse_persistent_identifier(pid)
             self.assertEquals(actual_result, expected_result)