Objectives : To analyze the effects of Samul-Tang and combinations of constituent herbs on arterial contraction. Method : In order to investigate the effects, Angelicae gigantis Radix, Cnidii Rhizoma, Rehmanniae Radix, Paeoniae Radix, in which one of them, three of them, and all of them, were used to exam. Results : Samul-Tang significantly inhibited the contraction of artery induced by PE(phenylephrine), accordingly as the concentration of Samul-Tang increased and inhibited in both with intact and removed endothelium. Among the constituent herbs of Samul-Tang, Paeoniae Radix and Paeoniae Radix-Cnidii Rhizoma combination inhibited the PE-induced contraction of artery the most. Conclusions : Samul-Tang and constituent herbs of Samul-Tang inhibit the contraction of artery