Acid and alkaline phosphatase (ACP and ALP) activities in plasma, testes and prostate, and sperm counts from cauda epididymis, were estimated in Wistar strain male rats treated with nicotine tartrate at a dose of 3 mg kg-1 b.wt day-1 for 14 days by subcutaneous injection. ACP activity in plasma, testes, and prostate increased significantly, while ALP activity in plasma and testes decreased significantly, in experimental animals as compared to respective controls. The sperm count declined significantly in both experimental groups. Nicotine may thus be implicated as a potent male reproductive toxin. The degree of toxicity increases in protein inadequacy.