Pharmacological actions of lisuride hydrogen maleate (lisuride) were studied by using isolated organs. 1) Lisuride at 2.2 microM exerted a negative chronotropic effect on guinea-pig atria, the effect being antagonized completely by 2.9 microM sulpiride. 2) alpha-Adrenolytic action of lisuride was observed in the rat vas deferens and beta-adrenolytic action in the rabbit trachea, respectively. The former (ID50 = 64 nM) was potent and equivalent to that of phentolamine, whereas the latter (ID50 = 26 microM) was only 1/30 as compared to that of propranolol. 3) Anti-5-hydroxytryptamine action (ID50 = 11 nM) was detected in the rat stomach and anti-histamine (ID50 = 15 nM) in the guinea-pig ileum, respectively. In these respective activities, lisuride was equipotent to methysergide and diphenhydramine. 4) Lisuride showed a spasmodic action, which may be categolized as an ergot alkaloid action, on the guinea-pig ileum and on rabbit renal artery. A weak positive inotropic action of lisuride was also observed in guinea-pig atria. In the rat uterus, however, no uterotonic action of lisuride was detected. It is concluded that, in addition to its known effects on the central nervous system, lisuride possesses potent peripheral anti-5-hydroxytryptamine and anti-histamine activities.