Intermittent antegrade warm blood cardioplegia (IAWBC) is a not usual technique of myocardial protection. We propose a delivery protocol that standardizes the length of ischemic intervals, duration of each cardioplegic dose and K+ amount. Cardioplegia is represented by blood, taken from the oxygenator and injected directly into the aortic root, and K+, added by means of a syringe pump. We reviewed the first 300 patients who underwent elective or urgent coronary artery by-pass procedures (group A) and compared them with the last 300 patients operated on with intermittent antegrade cold crystalloid cardioplegia (group B). The overall mortality in group A was lower than in group B (0.7 vs 3.0, p < 0.05); there was no in-hospital death in patients with poor left ventricle (LVEF < 35%) in group A (0/64 vs 3/39, p < 0.025). Reduction of mortality was due to a drastic fall of morbidity. In group A no patients needed circulatory assistance (13 in group B, p < 0.0005) or intraaortic balloon pumping (9 in group B, p < 0.005) in operating room or in intensive care unit (ICU); only 1 patient had inotropic drug (29 in group B, p < 0.0005) and only 6 needed lignocaine infusion (27 in group B, p < 0.0005). Incidence of postoperative myocardial infarction was lower in group A (4 vs 9 in group B) as well cerebrovascular accidents (4 vs 10 in group B), but difference was not statistically significant.(ABSTRACT TRUNCATED AT 250 WORDS)