Features of the pharmacological sensitivity of smooth muscles in the walls of arteries of the lesser circulation circle in rabbits with respect to cholinergic, histaminergic, and adrenergic agents, as well as the influence of endothelium on the realization of contractile response to these agents have been investigated in rabbits. A special feature in the cholinergic relaxation of smooth muscles of a pulmonary artery is a two-componential character of the dose dependence. The low-threshold component of the relaxant action of pilocarpine exhibits the endothelium-dependent character. An important feature of the contractile reaction to histaminergic action is a direct contractile effect of histamine, which is not observed in vessels of the greater circulation circle. Endothelium produces an inhibiting effect on the histaminergic contractility. The basic feature in the response to adrenergic action is the beta-adrenergic contractility effect. Activation of the cAMP-dependent alarm system in smooth muscles of the pulmonary arteries leads to a constrictive effect. The established features of the pharmacological sensitivity of smooth muscles of the artery walls of the lesser circulation circle are important for the clinical pharmacology.