Dolphins were photographed for individual identification purposes in Samadai reef, Marsa Alam, Red Sea between January 2012 and March 2013. In this study, 255 spinner dolphin Stenella longirostris were identified with a mean identification rate of 45%. Photo-identification analysis provided a population size range of 567 to 637 for spinner dolphins utilizing Samadai daytime for resting and socializing. From the 255 identified dolphins, 33 individuals (12.9%) were re-sighted for 4-8 times and 131 individuals (51.4%) were only observed once. The discovery curve indicated the continuous entrance of new animals to Samadai reef, which increased between May and December.