The influence of cisplatinum and goserelinum on the magnesium and calcium concentration in rat serum has been studied. The cisplatinum induces decrease in serum magnesium concentration (to 70%), and calcium concentration (to 63%). Goserelinum activity was similar to cisplatinum activity. The magnesium concentration decreased to 60%, and calcium to 44%. In condition of cisplatinum and goserelinum activity the hypomagnesemia and hypocalcemia were noted.