Despite the fact that numerous clinical trials investigating infarct size have been completed over the last two to three decades, the methods for treating lethal reperfusion injury efficiently have only become established very recently. After several years of accumulating evidence in experimental preparations that lethal reperfusion injury might exist, the description of the phenomenon of ischaemic post-conditioning in animal models has fully convinced us of the existence and importance of irreversible myocardial damage occurring after reflow. Transfer to the clinics was possible in small phase II trials, provided care was taken to assess the determinants of infarct size and, most importantly, to consider the timing of drug administration with respect to the time of reflow. Technical questions remain to be resolved regarding the assessment of the area at risk in the difficult setting of emergency care for reperfusion therapy. Nevertheless, convincing pharmacological trials are being performed that mark the start of a new era that will, in the future, improve the prognosis of patients with ST-segment elevation myocardial infarction through the prevention of lethal myocardial reperfusion injury. At present, while erythropoietin and adenosine have not proved efficient for alleviation of lethal reperfusion injury, a significant benefit has been reported for cyclosporin and exenatide. New pharmacological agents need to be identified and tested in phase II trials. In the meantime, clinical outcome studies are currently being conducted for cyclosporin.