These studies were carried out to investigate the effects of Ohotang water extract on the inhibitory contractile action of acetylcholine in control rat. The results of these were as follows; 1. Contractile force of acetylcholine from trachea smooth muscle in control rat was significantly inhibited by Ohotang. 2. Dose-response of acetylcholine pretreated Ohotang in control rat was significantly inhibited. 3. Inhibitory contractile action of acetylcholine pretreated propranolol in control rat was significantly inhibited by Ohotang. 4. Contractile force of acetylcholine pretreated indomethacin from trachea smooth muscle in control rat was not significantly changed. 5. Inhibitory contractile action of acetylcholine pretreated methylene blue in control rat was not significantly changed.