Nepeta suavis is used in traditional medicine for treatment of abdominal spasm (colic). The tricyclic clerodane type diterpene, nepetolide, isolated for the first time from Nepeta suavis, was evaluated for Ca++ antagonist and antispasmodic activities. When studied in isolated rabbit jejunum, nepetolide caused concentration-dependent (0.03-100 μM) relaxation of spontaneous and high K+ (80 mM)-induced contractions, like that caused by verapamil, indicating that nepetolide exhibits spasmolytic activity, possibly mediated through Ca++ channel blocking action, which provides scientific explanation for the medicinal application of Nepeta suavis as an antispasmodic agent.