This study investigated the ultrastructural effects of daily oral doses of nickel sulphate (NiS04) (12.5mg/kg) on rat testis seminiferous tubules on days 15, 60 and 95 of the experiment. The latter constituted the recovery group. The seminiferous tubules were severely damaged on the 15th and 60th days. The major findings were the germ cell sloughing and decreased spermatogenesis. A disorder in germ cell alignment was evident. Sertoli cell's phagocytic activity was increased. Recovery which was aimed to be established on the 95th day following a 60 day- NiSC>4 administration could not be observed at theseminiferous tubules of that group.