We examined seasonal variations in liver condition factor, total lipid and fatty acid composition of maturing pikeperch (Sander lucioperca) from Lake Egirdir, Turkey. The spawning of pikeperch in Egirdir Lake started in March, continued very fast during May and gradually ended in July as determined by measuring the gonadosomatic index. The total lipid content of male and female liver reached its highest level in September and November (the end of dense feeding period during which temperature decreased sharply), but declined to the lowest level in May Oust after spawning). The highest level of liver condition factor was observed in January and March during which gonads mature rapidly. Palmitic acid was the predominant saturated fatty acid (SFA) in female and male liver. The ratio of monounsaturated fatty acids (MUFA) was higher than that of polyunsaturated fatty acids (PUFA) in both sexes. Docosahexaenoic acid (22:6n-3), eicosopentaenoic acid (20:5n-3) and arachidonic acid (20:4n-6) were the predominant PUFA. Seasonal variations in PUFA were more evident than that in other fatty acids. PUFA, especially the n-3 fatty acids ratio, increased to the maximum level during the sharp decreases in temperature (in November). However, the amount of PUFA decreased to the lowest level in reproductive period. The results suggest that the ratio of pikeperch liver fatty acids is influenced by gonad maturation and temperature variations and that pikeperch requires a large amount of PUFA and the n-3 fatty acids for the development of gonads.