diff --git a/kafka/client.py b/kafka/client.py
index a683fe006..375272f09 100644
--- a/kafka/client.py
+++ b/kafka/client.py
@@ -255,6 +255,8 @@ def load_metadata_for_topics(self, *topics):
             self.topic_partitions[topic] = []
             for partition, meta in partitions.items():
                 topic_part = TopicAndPartition(topic, partition)
+                if meta.leader == -1:
+                    raise PartitionUnavailableError("Leader is unassigned for %s-%s" % (topic, partition))
                 self.topics_to_brokers[topic_part] = brokers[meta.leader]
                 self.topic_partitions[topic].append(partition)