Glyphosate (GLP) is a globally spread herbicide that causes many public health disorders through induction of oxidative stress. The present study aimed to investigate the harmful effect of GLP at the testicular ultrastructural level and to evaluate the possible protective effect of N-acetylcysteine (NAC) against such toxicity. Thirty adult male albino rats were divided into 3 groups (10 rats/group).Group I served as a negative control group received distilled water only, Group II orally administered (375 mg/kg) GLP and Group III orally administered NAC (160mg/kg, one hour before GLP) plus GLP (the same dose of group II) daily for 6 weeks. Testes were collected and fixed in glutaraldehyde then were processed for transmission electron microscopy. Examination of ultrathin sections of testicular tissue vacuolation, mitochondrial degeneration, nuclear condensation, increase intercellular spaces and deformed spermatozoal heads and tails with excess residual bodies. On the other hand, examination of ultrathin sections of testicular tissue from NAC co-treated rats revealed partial disappearance of most degenerative changes induced by GLP. In conclusion, GLP exerts some deleterious effects on testicular structure and the concurrent administration of NAC can ameliorate these detrimental effects.