The convulsant action of cocaine and the proconvulsant effects of sildenafil, a drug which is widely used in the treatment of erectile dysfunction, have been documented both in humans and mice. Since it was reported that sildenafil alone, and in conjunction with cocaine, is used recreationally, the present study was performed to examine the influence of sildenafil on cocaine-induced seizures in mice.We showed that administration of sildenafil (5-20 mg/kg, ip) did not affect latency to clonic seizures induced by ip administration of cocaine at a dose of 85 mg/kg, nor did it influence seizure incidence and mortality.We conclude that sildenafil does not significantly increase the risk of seizures when co-administered with cocaine.