Aqueous extract of Spondias mombin in different dilutions was employed to assess its impact on male reproductive, haematologic and biochemical indices of male albino rats. A single daily intragastric administration of 8.4, 16.8 and 33.6 mg kg^-1 body weight day^-1 of the extract for 4 weeks did not cause any adverse effect on body and organ weights except a slight increase in liver weight. There was a marked dose-dependent reduction in epididymal sperm progressive motility, sperm count, viability (live/dead ratio) and a dose-dependent increase in percentage of abnormal spermatozoa. Abnormalities like double heads, double tails, detached heads and broken tails were frequently observed. Epididymal α-glucosidase activity was significantly reduced. However, prostatic acid phosphatase activity and citric acid levels and seminal fructose concentrations remained unchanged following Spondias mombin treatment. Blood analysis showed that red cell and white cell counts and haematocrit (Hct) levels were in the normal range. Bilirubin, serum glutamate pyruvate transaminase [alanine aminotransferase], serum glutamate oxaloacetate transaminase [aspartate aminotransferase], urea and protein concentrations were slightly altered by Spondias mombin extract. Discontinuation of the extract resulted in full recovery within 4 weeks of treatment cessation. The results suggest that aqueous extract of the bark of Spondias mombin has reversible antifertility action, the testis and the epididymis probably being the prime sites of action.