The present study investigated the effect of the GABA(B) receptor antagonist, SCH 50911 [(2S)(+)-5,5-dimethyl-2-morpholineacetic acid], on the occurrence of seizures in ethanol-dependent rats undergoing ethanol withdrawal syndrome. The acute administration of nonconvulsive doses of SCH 50911 (0, 100, 170 and 300 mg/kg, i.p.) resulted in a dramatic facilitation of spontaneous seizure occurrence. This finding, together with the reported ability of the GABA(B) receptor agonist, baclofen, to suppress seizures associated to ethanol withdrawal syndrome, suggests that the GABA(B) receptor may be part of the neural substrate underlying the hyperexcitability of ethanol withdrawal syndrome.