Abstract: Pachycarpine given intravennously (20～40 mg/kg) to anesthetized rabbits and cats markedly increased the force of contraction of the anterior tibialis musculi for 20～60 minutes (P<0.01). Pachycarpine at 10^-4 or 2×10^-4g/ml markedly increased the force of contraction of the isolated rat diaphragm(P<0.01). It's action of excitation of musculi skeleti differed from that of neostigmine because pachycarpine did not influence the cholinergic system. After denervation of the rabbit nervi peronaeus communis pachcarpine still showed excitation of the anterior tibilis musculi and the action intensity was less than that before denervation.