The effects of an aqueous extract of Carica papaya seeds (20 mg/kg body weight/animal/day orally and 5 mg/kg body weight/animal/day i.m. for 60 days) were investigated for contraceptive efficacy and other related side effects in male albino mice, Mus musculus. The data revealed that the extract might be causing an androgen deprived effect to target organs resulting in alterations in the internal milieu of the cauda epididymis especially. The treatment did not, however, affect the testicular sperm count suggesting that it acted at the post-testicular level which lead to a reduction of cauda epididymal sperm motility and thus the treatment brought about a significant reduction in fertility rate. The induced effects were transient and reversible upon withdrawal of the treatment, elucidating that functional sterility could be induced by the aqueous papaya seed extract in rodents.