Abstract: The pharmacological actions of dehydrocorydaline (DHC) isolated from Chinese medicine Yan Husuo (Corydalis Yanhusuo) on cardiovascular system have been observed and compared with those of tetrahydropalmatine (THP).DHC was shown to be more active than THP in increasing the tolerance of mice to monobaric and hypobaric hypoxia.In anesthetized open-chest cats, the coronary venous flow was enhanced by iv DHC 1 mg/kg, but the heart rate was slowed slightly, whereas THP only exhibited a negative effect. After administration of DHC, the myocardial uptake of ⁸⁶Rb in mice was increased. The protective actions on change of ECG induced by pitutrin, and on experimental myocardial necrosis induced by isoproterenol were observed. THP, however, exerted no marked effect.Both DHC and THP showed similar sedative and anticonvulsive effects on CNS, but the action of DHC was weaker and more lasting.From these findings, it appears that DHC is one of the active principles of Yanhusuo for the treatment of coronary heart disease.