This study was prospectively designed to determine the physiologic effects of normothermic CPB and to compare its influences with hypothermic CPB. Material and Method: Thirty-six adult patients scheduled for el­ective cardiac surgery were randomly assigned to moderate hypothermic (hypothermic group nasopharyngeal tem­perature $26~28^{circ}C,;n=18)$ ornormothermic (normothermic group, nasopharyngeal temperature > $35.5^{circ}C;n=18)$ CPB. Arterial blood samples were taken before CPB (Pre-CPB), 10 minutes after the start of CPB (CPB-10), and imme­diately after CPB stop (CPB-off) for determining total leukocyte counts, neuron-specific enolase (NSE), interleukin-6 (IL-6), endothelin-1 (ET-1), cortisol, troponin I (TNI), aspartate aminotransferase (AST), alanine aminotransferase (ALT), creatinine, blood urea nitrogen (BUN), and the pulmonary index $(Pi,;PaO_{2}/FiO_{2}),$Other parameters such as urine output, mechanical ventilating period, ICU-staying period, postoperative complications and hospitalized days were also evaluated. Result: Total leukocyte counts, increased rate in NSE, in IL-6 and in cortisol at CPB-10 and CPB-off were significantly higher in normothermic group than in hyphothermic group. Urine output during CPB was lower in normothermic group than in hyphothermic group. The duration of mechanical ventilation, ICU-stay, and hospitalization were longer in normothermic group than in hyphothermic group. Conclusion: These findings sug­gested that normothermic CPB caused higher inflammatory and stress responses than hypothermic CPB during car­diac surgery using cold crystalloid cardioplegia. However, further studies with large number of cases should be carried out to validate this hypothesis.