At the most severe end of the spectrum of acute coronary syndromes is ST-segment elevation myocardial infarction(STEMI), which usually occurs when a fibrin-rich thrombus completely occludes an epicardial coronary artery. Timely reperfusion therapy is the best and the most important component of the treatment for STEMI. Several randomized trials and meta-analysis have shown that primary percutaneous coronary intervention(PPCI) is superior to thrombolysis in STEMI therapy. However, PPCI should be regarded as preferred strategy only within a reasonable time delay from onset to treatment, in contrast to thrombolysis. There is a continuing controversy about the acceptable time-window for PPCI in patients with STEMI. Recent American and European guidelines recommend PPCI if the delay in performing PPCI instead of administering fibrinolysis (PCI-related delay) is 60 minutes and the presentation delay is more than 3 hours. Based on a review of the literature, the evidence supports an acceptable PCI-related delay of 80-120 min and PPCI as a better reperfusion strategy also in the high-, medium- risk patients and early incomers. Furthermore, To maximize the number of patients with STEMI eligible for PPCI, the optimal logistic strategy could be the confirmation of the diagnosis in the prehospital phase, to bypass local hospitals, and to re-route patients directly to facilities that can administer catheterization. To obtain the maximal benefit for survival, the optimal antithrombotics and adjuvant drug therapy is necessary.