The effects of season and sex on the fatty acids (FAs) and proximate compositions of the mantle of the mature common cuttlefish were evaluated. The results of the proximate composition showed that the lowest lipid content was obtained from females in winter (0.74%), whereas the highest level of lipid was found in males in autumn (0.94%; p < 0.05). The protein levels of the mantle of the mature male of common cuttlefish were significantly higher (p < 0.05) than those found in female specimens. The FA compositions of each sex for all seasons ranged from 29.4% to 32.5% saturated FAs, 8.7-11.1% monounsaturated FAs and 48.2-54.6% polyunsaturated fatty acids (PUFAs). The proportions of n-3 PUFAs (44.0-50.6%) were higher than n-6 PUFAs (3.4-4.3%) regardless of sex and seasons. The levels of eicosapentaenoic acid in the mature common cuttlefish mantle in spring, autumn and winter were 15.9-17.8%, 16.3-17.2% and 15.7-16.8% while those of docosahexaenoic acid were 32.5-33.0%, 27.5-29.0% and 28.7-31.1%, respectively.