Background and objectives: Normothermic cardiopulmonary bypass has been proposed as a more physiologic technique than hypothermic bypass for the maintenance of the body during cardiac surgery. Methodology: Fifty patients who had mitral valve surgery in our institute were prospectively divided into two groups: Group A (n=25) received intermittent antegrade warm blood cardioplegia, and Group B (n=25) received intermittent antegrade cold blood cardioplegia with systemic hypothermia. Clinical and metabolic studies have been carried to evaluate the efficacy of myocardial protection in both groups. Results: No differences were found between the two groups as regards the mortality, intubation time, total ICU stay time and the duration of inotropic support post operatively. However, the hypothermic group needed more defibrillation in the reperfusion period, more inotropic support to wean off bypass, and had more chest tube drainage. There was no difference in the postoperative level of CK and CK-MB between the two groups; however troponin I release was higher in the cold group. There was also no difference in the ventricular performance at follow up. Conclusion: Intermittent antegrade warm blood cardioplegia is a safe alternative to the standard intermittent antegrade cold blood cardioplegia, but it was not proved to provide superior myocardial protection in mitral valve surgery.