Effect of electrcal stimulation and several autonomic drugs on the isolated vagina uteri muscle strips of the hen were investigated. Electrical stimulation elicited relax- ation of the muscle in most cases, and only in a few cases it was then followed by a weak contraction. The responses to electrcal stimulation were completely abolished in the presence of tetroditoxin. The relaxation response to electrical stimulation was reversed, in the presence of dichloroisoproterenol(DCI), to a contraction response which was then markedly reduced after administration of regitine or atropine. Norepi- nephrine caused relaxation of the muscle, and this was reversed, in the presence of DCI, to a contraction which was then abolished and the relaxation reappeared after administration of regitine, Acetylcholine elicited contraction of the muscle, and this was abolished in the presence of atropine. These results suggest that the vagina uteri muscle of the hen is innervated by both adrenergic and cholinergic fibers, and the former is more dominant than the latter eliciting the muscle response; and that muscle α-and β-receptors which mediate contraction and relaxation, respectively. However, the β-receptor is more predominant than the α-receptor.