The effect of clenbuterol, a selective beta 2-adrenoceptor agonist, on isolated periurethral striated muscle preparations from rabbits has been investigated. The periurethral striated muscle produced a contraction in response to field stimulation. An application of clenbuterol resulted in a dose-dependent potentiation of the field stimulation-induced contraction. This potentiation was antagonized by propranolol and was greater than that of isoproterenol, suggesting a beta 2-agonistic action.