Propofol is a short acting, rapidly metabolized intravenous anesthetic agent. It cause a decrease in arterial pressure after induction of anesthesia and a decrease in heart rate. Hypertension, tachycardia during induction of anesthesia or in response to tracheal intubation is undesirable in high-risk patients, Propofol might attenuate the pressor to tracheal intubation than thiopental. In this study we compared propofol with thiopental for induction of anesthesia. Forty patients of ASA class III scheduled to undergoing valvular replacements divided two groups. Twenty patients were induced with thiopental, twenty patients were induced with propofol and maintained using 50% nitrous oxide in oxygen. Cardiovascular parameters were checked before induction, after propofol or thiopental injection, after succinylcholine injection, after tracheal intubation, after isoflurane mixed inhalations. The aim of this study is to examine a camparison of hemodynamic effects between propofol and thiopental for valvular replacement. The results were as follows. 1) There is little change in heart rate with thiopental group, but heart rate was decreased in propofol group. 2) There is slightly deaeased in arterial pressure with thiopental group, but markedly decreased in propofol group. 3) There is no difference of central venous pressure between two groups.