The purpose of this study is to examine the effects of sasang constitutional herbal extracts such as Yangkyuksanhwatang(YST) on EKG. For this purpose, 3 hospitalized Soyangin patients having heart disease history was selected. and changes of the symptoms and EKGs was investigated. We measured and observed EKG changes of before YST medication and after medication. The results of these experiments were as follows. 1. The activity of HR, PR, QRS was decreased on EKG2 comparison to EKG1 after Yangkyuksanhwatang(YST) medication 2. QT, QTC interval was prolonged after YST medication 3. RR time was prolonged after YST medication 4. The voltage of Q wave was decreased after YST medication From the above results, it is suggested that Yangkyuksanhwatang(YST) have influenced on EKG.