Adult male albino rats were treated with 0.5 mg and 0.75 mg morphine/100 g body weightintraperitoneally for 30 days. All the animals were autopsied on 31st day. Epididymis and vasdeferens were dissected out, weighed and processed for histological and biochemical studies.Morphine has caused a reduction in the weight of epididymis and vas deferens in both the dosesof drug treated groups. The total cholesterol content is increased while protein, DNA and RNAcontents and epididymal sperm counts are decreased. The acid phosphatase content is decreased10.12 ± 0.11 in caput, 9.26 ± 0.30 in cauda of epididymis and in vas deferens 8.14 ± 0.15 in 0.5 mgtreated groups and in 0.75 mg treated rats shows 9.52 ± 0.27 in caput, 9.14 ± 0.18 in cauda ofepididymis and in vas deferens 7.84 ± 0.11is decreased, whereas alkaline phosphatase isincreased. The surface epithelial cell height of these ducts is reduced and secretory activity isinhibited with the disruption of epithelial cell projections. The gravimetric and histometricchanges of epididymis and vas deferens may be due to non-availability of androgens in morphinetreated rats.