Background: In cardiac surgery, hypothermia is associated with a number of major disadvantage, including its detrimental effects on enzymatic function, energy generation and cellular integrity. Warm cardioplegia with normothermic cardiopulmonary bypass cause three times more incidence of permanent neurologic deficits than the cold crystalloid cardioplegia with hypothermic cardiopulmonary bypass. Interruptions or inadequate distribution of warm cardioplegia may induce anaerobic metabolism and warm ischemic injury. To avoid these problems, tepid blood cardioplegia was recently introduced. Material and Method: To evaluate whether continuous tepid blood cardioplegia is beneficial in clinical practice during valvular surgery, we studied two groups of patients matched by numbers and clinical characteristics. Warm group(37$^{circ}C$) consisted of 18 patients who underwent valvular surgery with continuous warm blood cardioplegia. Tepid group(32$^{circ}C$) consisted of 17 patients who underwent valvular surgery with continuous tepid blood cardioplegia. Result: Heartbeat in 100% of the patients receiving continuous warm blood cardioplegia and 88.2% of the patients receiving continuous tepid blood cardioplegia converted to normal sinus rhythm spontaneously after removal of the aortic cross clamp. There were no differences between these two groups in CPB time, ACC time, the amount of crystalloid cardioplegia used and peak level of potassium. During the operation, the total amount of urine output was more in the warm group than the tepid group(2372${pm}$243 ml versus 1535${pm}$130 ml, p<0.01). There were no differences between the two groups in troponin T level measured 1hr and 12hrs after the operation. Conclusion: Continuous tepid blood cardioplegia is as safe and effective as continuous warm blood cardioplegia undergoing cardiac valve surgery in myocardial protection.