Muscles of roach (Rutilus rutilus L.), bream (Abramis brama L.), perch (Perca fluviatilis L.), pike (Esox lucius L.), vendace (Coregonus albula L.) and whitefish (Coregonus lavaretus L.) from lakes of the Olsztyn Lake District were examined for the content of macroelements (Mg, Ca, Na, K and P) and microelements (Fe, Zn, Cu and Mn). The fish were caught over the period from October 1999 to October 2000. There were significant interspecific differences in the contents of dietary elements. The highest magnesium (26.7 mg/100 g), calcium (36.5 mg/100 g) and phosphorus (230.6 mg/100 g) concentrations were found in the muscle of roach. A significantly higher content of Mg was observed in the muscle of pike (27.6 mg/100 g) and perch (26.5 mg/100 g). The concentration of Na (47.0 mg/100 g) in muscle tissue of perch was higher than in that of the other fish species. The significantly higher contents of Fe (2.81 mg/kg), Cu (0.315 mg/kg) and Mn (0.167 mg/kg) were found in muscle of vendace. In the muscle tissue of pike, the concentrations of zinc (8.41 mg/kg) were higher compared with other species.