Exposure to pesticide chlorpyrifos (CPF) has been implicated in reproductive deficits in both humans and animals. Diphenyl diselenide (DPDS) is an organoselenium compound widely reported to elicit potent pharmacological activities in several chemically-induced toxicity and disease models. However, there is paucity of scientific information on the influence of DPDS on CPF-induced reproductive dysfunction. The present study investigated the influence of DPDS on CPF-induced functional changes along the hypothalamic-pituitary- testicular axis in rats. CPF was administered alone at 5 mg/kg body weight or orally co-treated with DPDS at 2.5 and 5 mg/kg body weight for 35 consecutive days. Results showed that DPDS co-treatment significantly (p < 0.05) abrogated CPF-induced oxidative stress by increasing the antioxidant enzymes activities and glutathione content, decreasing the hydrogen peroxide and lipid peroxidation levels in the hypothalamus, testes and epididymis of the treated rats. Moreover, DPDS co-treatment significantly ameliorated CPF-induced histological alterations in the hypothalamus, testes and epididymis of the treated rats. Besides, the significant augmentation of luteinizing hormone, follicle-stimulating hormone and testosterone levels as well as the testicular activities of acid phosphatase, alkaline phosphatase and lactate dehydrogenase by DPDS was accompanied by an increase in sperm quality and quantity in the treated rats. Taken together, DPDS abrogates CPF mediated toxicity along the hypothalamic-pituitary-testicular axis in rats via inhibition of lipid peroxidation, enhancement of antioxidant enzymes activities and testicular function. Thus, DPDS may be a possible chemoprotective drug candidate against CPF-induced male reproductive deficits in humans. (C) 2018 Published by Elsevier