The aim of this paper is to establish the chronology of the sanctuaries of Sarapis on Delos, particularly the Sarapieia A and B, thus attempting a more precise history of the Isiac cults on the island. The excavation that was conducted during the summer of 2014 in the Sarapieia A and B , and the study of the material found during this campaign, provide new clues to write their architectural history and help to answer this major question: which was the first Sarapieion built in Delos, and when was it founded?