This paper deals with the issue of the expansion of the Mediterranean Judaism in association with the Synagogue of Delos. After presenting in brief the expansion of the Jews in the Mediterranean Sea the research focuses on the history of the island of Delos and the presence of the Jews on it. The presence of the Jews on the island is associated with the building GD 80. The paper examines the question of the identification of the building as a synagogue focusing in elements as topography – situation, chronology, inscriptions and secondary fittings or findings. It presents the various opinions of the scholars who dealt with the subject and attempted to testify if the building GD 80 is the oldest synagogue of the Diaspora. The paper proposes the examination of the synagogue of Delos in parallel with the synagogue of Ostia and those of the Diaspora and the comparison of it with the synagogues of the land of Palestine.