The most commonly-consumed cephalopods around the world (the common cuttlefish, Sepia officinalis, European squid, Loligo vulgaris, common octopus, Octopus vulgaris and musky octopus, Eledone moschata) were evaluated in terms of seasonal variations in proximate and fatty acid compositions. The arms of the octopuses were used for this study, whereas the mantle of the other species (squids and cuttlefish) were used for the analyses. The lipid contents of species were found to be very low and considered as lean. The lowest lipid content was obtained from E. moschata (0.60-0.68%), whereas L. vulgaris gave the highest level of lipid (1.34-1.92%) throughout all seasons. Unlike lipid content, protein contents of cephalopods did not change across the seasons. The fatty acid compositions of each species ranged from 28.18% to 35.28% saturated (SFA), 4.36-9.47% monounsaturated (MUFAs) and 43.58-56.55% polyunsaturated acids (PUFAs). The highest proportions of fatty acids in cephalopods were myristic acid (C14:0, 0.96-2.96%), palmitic acid (C16:0, 15.53-25.20%), heptadecanoic acid (C17:0, 1.05-2.56%), stearic acid (C18:0, 4.32-9.96%), oleic acid (cis18:1 n-9, 1.80-4.29%), cis-11-eicosenoic acid (C20:1, 2.07-4.69%), linoleic acid (C18:2 n-6, 0.17-1.95%), arachidonic acid (C20:4 n-6, 1.48-11.65%), cis-5,8,11,14,17-eicosapentaenoic acid (EPA, C20:5 n-3, 7.86-16.97%) and cis-4,7,10,13,16,19-docosahexaenoic acid (DHA, C22:6 n-3, 20.99-39.00%). The results indicated that these cephalopod species are excellent protein sources and very rich in n-3 fatty acids. (c) 2007 Elsevier Ltd. All rights reserved.