These studies were carried out to investigate the effect of Jungchuntang water extract on the inhibitory contractile action of acetylcholine in rat. The results of these studies were as follows; 1. Contractile force of acetylcholine from trachea smooth muscle in rat was significantly inhibited by Jungchuntang. 2. Dose-response of acetylcholine pretreated Jungchuntang in rat was not significantly changed. 3. Inhibitory contractile action of acetylcholine pretreated propranolol in rat was decreased. 4. Inhibitory contractile action of acetylcholine pretreated indomethacin was not significantly changed by Jungchuntang. 5. Inhibitory contractile action of acetylcholine pretreated methylene blue was significantly changed by Jungchuntang. 6. Contractile force of acetylcholine from trachea smooth muscle in rat was significantly inhibited by Jungchuntang. 7. Dose-response of acetylcholine pretreated Jungchuntang in rat was not significantly changed. 8. Inhibitory contractile action of acetylcholine pretreated propranolol in rat was decreased. 9. Inhibitory contractile action of acetylcholine pretreated indomethacin was not significantly changed by Jungchuntang. 10. Inhibitory contractile action of acetylcholine pretreated methylene blue was significantly changed by Jungchuntang.