The antirenotropic activities of three antiandrogens which are frequently used in the clinical praxis (cyproterone acetate, flutamide and casodex) and of natural endogenous antiandrogen epitestosterone were compared. The substances were administered in oil intraperitoneally to intact male mice. The weight of kidneys was decreased most effectively by casodex and epitestosterone, though the antiandrogenic activity expressed by the decreased weight of seminal vesicles was confirmed in all preparation tested, except for flutamide. Only epitestosterone significantly reduced the level of plasma testosterone, whereas casodex increased testosterone level in plasma. LH level was decreased by testosterone propionate and epitestosterone significantly, but about 50 percent increase in the mean LH level in casodex treated animals did not reach the statistical significance.