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