by malathion in renal tissue compared to those induced by malathion plus antioxidants, to clarify the underlying mechanisms, using immunohistochemical staining of proliferating cell nuclear antigen [PCNA] and CD34 Methods: Forty adult male albino rats were divided into four equal groups. Group 1; control. Group 2 received malathion [27 mg/kg/day] orally. Group 3 received malathion plus vitamin E [400 mg] once/day, orally. Group 4 received malathion plus vitamin C [100 mg,] once/day, orally. Animals of all groups were sacrificed after 2 months. Histopathological assessment [H and E and Masson 's trichrome] , PCNA and CD34 immunostaining were performed to all groups Results: Group 2 showed a spectrum of histopathological changes; collapsing glomerulopathy with focal sclerosis, degenerative tubular changes and diffuse vascular congestion. Both groups 3 and 4 showed marked reduction of previous changes. Masson 's trichrome stained sections showed more collagen deposition in group 2 compared to groups 3 and 4. Group 2 revealed a decrease in the mean number of total PCNA positive cells [20.8 +/- SD 5.7] [P< 0.001] compared to control group. Groups 3 and 4 showed high significant increase in the mean number of total PCNA positive cells [31.3 +/- SD 5.7 and 31.2 +/- SD7.8] [P<0.001 and 0.004, respectively] . CD 34 immunoslaining of group 2 showed negative to minimal expression compared to moderate to strong intensity of groups 3 and 4