The aim of this study was to analyze seasonal variation of levels of Chromium (Cr), Manganese (Mn), Nickel (Ni), Copper (Cu), Zinc (Zn), Cadmium (Cd) and Lead (Pb) in water, sediment and tissues of Squalius cephalus (L., 1758) taken from five different stations chosen at Yamula Dam Lake (Kayseri, Turkey). Concentrations of metals were generally sorted as water < tissue < sediment. The highest concentration of metals in water was observed in the samples taken in the summer (Mn, 1.04 +/- A 0.15 mg L-1; Ni, 0.42 +/- A 0.12 mg L-1; Cu, 1.25 +/- A 0.88 mg L-1; Zn, 3.61 +/- A 1.53 mg L-1; Pb, 0.58 +/- A 0.09 mg L-1). While the highest Zn (24.85 +/- A 21.82 mu g g(-1)) and Pb (10.89 +/- A 4.2 mu g g(-1)) concentrations in sediment were observed in the winter samples, the highest Mn concentration (167.2 +/- A 99.37 mu g g(-1)) was observed in the summer. Cd pollution was determined in sediment according to international criteria. The highest metal concentration in tissues was generally observed in the liver and the other tissues; following liver were gills and muscles. In liver tissues, while the highest accumulation of Zn (110.34 +/- A 13.1) and Mn (22.5 +/- A 14.85 mu g g(-1)), which are essential for the body, were observed in the winter, Pb (22.58 +/- A 7.83 mu g g(-1)) and Cd (11.77 +/- A 7.83 mu g g(-1)), which are toxic, were found to be higher in the summer. Also, concentrations of Mn, Cd and Pb in muscle tissues were found to be above the limits permitted.