The soft-bottom crustacean fauna from Izmir Bay was studied semi-annually between September 2014 and April 2016. Benthic samples were collected by means of a Van Veen grab, sampling ca. 0.1 m(2) area, at 4 stations in the inner (3 stations) and middle (a single station) parts of the bay. Forty-one species and 999 individuals belonging to seven crustacean orders (Sessilia, Mysida, Amphipoda, Cumacea, Tanaidacea, Isopoda, Decapoda) were identified. Amphipoda were represented with the highest number of species (21 species) followed by Isopoda (7) and Decapoda (6). Among the species encountered, Phtisica marina was the most dominant species with an average 90.6 individuals (27.22% of the total number of individuals) while Iphinoe douniae was the most frequent species (occurring in 50% of the samples). Eurycarcinus integrifrons De Man, 1879 is an alien decapod herein reported for the first time from the Aegean Sea.