The objective of the present study was to determine chemical composition of carapace meat of male and female mature blue swimmer crabs, Portunus pelagicus, caught in the Mersin Bay. The levels of protein ranged from 20.75% to 23.44%, lipid from 1.13% to 1.43%, and water from 73.31% to 76.04%, total mineral substance (TMS) from 1.81% to 2.10% for blue swim-mer crabs. Statistically, carapace meat of female blue swimmer crabs had higher protein level, and lower lipid, water and TMS levels than those of the male (p0.05). Besides, statistically, there were significant differences in palmitoleic acid, oleic acid, arachi-donic acid, EPA and DHA levels in carapace meat of male and female blue swimmer crabs (P0.05). EPA levels of female blue swimmer crabs (21.09%) were higher than male blue swimmer crabs (20.56%). Furthermore, DHA levels of male blue swimmer crabs (14.57%) were higher than female ble swimmer crabs (12.41%). The PUFA/SFA and n-6/n-3 was de-tected as 1.77, 0.28 for female blue swimmer crabs whereas it was 1.82, 0.27 for male blue swimmer crabs, respectively. In the present study, it was observed that carapace meat of blue swimmer crabs were contaminated with Cu and Zn.