A review of the first 52 consecutive coronary artery bypass surgery patients to receive oxygenated blood cardioplegia, with warm reperfusion cardioplegia ('hot shot'), was undertaken to evaluate its effectiveness in myocardial protection. The chosen parameters of ischaemia were: (i) the occurrence of ventricular fibrillation (VF) on release of the aortic cross-clamp (ACC); (ii) the occurrence of bradycardia due to cardiac conduction defects; (iii) the use of inotropes with or without the use of the intra-aortic balloon pump (IABP); (iv) evidence of myocardial infarction (MI) on the postoperative electrocardiograph (ECG); and (v) peri-operative cardiogenic mortality. Warm induction cardioplegia was cooled after cardiac standstill. Repeat cold cardioplegia was given as required at intervals and warm reperfusion cardioplegia was given prior to release of the ACC. Of the 52 patients studied none developed VF after release of the ACC; one patient with pre-operative complete heart block required temporary cardiac pacing; no patient required inotropes or IABP and there was no postoperative MI or mortality. The warm blood cardioplegia technique has not resulted in any detectable evidence of inadequate myocardial protection. A beneficial effect has been demonstrated by the absence of VF, cardiac conduction defects, myocardial failure, MI and mortality.