In anesthetized rats, SKF 38393 (10 mg/kg, i.v.) did not facilitate urinary bladder motility, but bromocriptine (BR, 5 mg/kg, i.v.) alone and the combination of BR (1 mg/kg, i.v.) and SKF 38393 (1 mg/kg, i.v.) induced a hyperactive bladder response (HBR). Both HBR induced by BR alone or BR and SKF 38393 combined was suppressed by SCH 23390. sulpiride or haloperidol. These results indicate that HBR is mediated by the activation of D-2 receptors, and the effects of D-2 agonists on bladder motility are potentiated by the simultaneous stimulation of D-1 receptors.