Abstract: Bisatropinium bromide(BA), 1, 4-diethoxybenzene-bis-atropinium dibromide, is a new muscle relaxant synthesized with atropine. This paper reports the results of pharmacological studies.In rabbits, the head-drop dose of BA was found to be 0.13±0.029 mg/kg(ⅳ). In sciatic-tibialis anterior preparations of anesthetized cats, the neuromuscular blocking dose of BA was 0.16±0.029 (?)g/kg(ⅳ), with a duration of 21±3.9 min. The evidences obtained by classical and electrophysiological methods indicate that BA is a non-depolarzing muscle relaxant.When BA(1.4 x head-drop dose) was administered repeatedly to conscious rabbits for 9 times within 2.5 h, certain accumulative effect was observed. Nevertheless, all animals recovered without deleterious effect. Bolus intravenous injection of BA at a neuromuscular blocking dose produced a trancient hypotension in anesthetized cats, but seldom in rabbits. The hypotensive effect of BA could be nullified to a slight degree by administering the drug through slow intravenous drip. Further experiments showed that the hypotensive effect in cats was chiefly mediated by its sympathetic ganglion blocking action. In anesthetized cats, doses of BA sufficient to produce a complete muscle paralysis provoked no marked ECG changes. BA retained feeble antimuscarinic activity.On account of its high potency, suitable duration of action and relative safety shown in animal experiments, we think that BA may be a new muscle relaxant of potential clinical value.