Oxidative stress is one of the molecular mechanisms involved in chlorpyrifos (CPF) and lead poisoning. The present study investigated the role of vitamin C in mitigating the biochemical alterations induced by co-administration of CPF and lead. Forty adult male Wistar rats divided into 4 groups of 5 animals in each group were used for this study. Group I was dosed with corn oil (2 ml/kg) while group II was given vitamin C (100 mg/kg). Group III was co-administered CPF ( 4.25 mg/kg~ 1/20th LD50) and Pb (225 mg/kg~1/20th LD50) while group IV was pretreated with vitamin C (100 mg/kg) and then co-administered with CPF (4.25 mg/kg) and Pb (225 mg/kg), 30 min later. The regimens were administered once daily by oral gavage for a period of 9 weeks. The rats were sacrificed and sera obtained from the blood samples were analyzed for the total proteins, albumin, globulin, electrolytes (Na+, K+, Cl-), urea and liver malonaldehyde concentrations. The activities of serum aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, gamma-glutamyl transferase and lactate dehydrogenase were evaluated. The result showed that alterations in the biochemical parameters induced by co-exposure to CPF and lead were mitigated by pretreatment with vitamin C.