Studies on testes and epididymis tissue of rats treated orally for fourteen days with therapeutic doses of cloxacillin (6mg/100g/day), ampicillin (4mg/100/day) and tetracycline (12mg/100g/day) separately showed a significant reduction in testicular and epididimis architecture. Microscopic studies of these male reproductive organs further revealed a significant alteration in the epididymis as revealed by a significant reduction (p < 0.05) in epididymal ductular diameter (EDD), and epididymal epithelial height (EEH) in treated group of animals. A significant increase (p < 0.05) was however recorded in epididymal luminal diameter (ELD) in all the animals after the two and three week's recovery period allowed. This gives another insight into the toxicity activities of these antibiotics on male reproductive organs, apart from reduction in serum testosterone level, decreased sperm motility, decreased spermatozoa count and decrease in RNA and DNA content of spermatogenic cells as earlier reported.