Aims: The aim of this study was to evaluate treatment with primary percutaneous coronary intervention (PCI) in unselected patients with ST-segment elevation myocardial infarction (STEMI). Methods: We registered complication and mortality rates in all patients with STEMI admitted for primary PCI at a high-volume center over a two-year period (2004 to 2006). Results: We included 1022 consecutive patients (mean age 64 years; 69% men). In-hospital and one-year mortality were 8% and 12%, respectively. Cardiac arrest, cardiogenic shock, left ventricular ejection fraction ≤40% and atrioventricular block significantly predicted increased one-year mortality in univariate analysis (P < 0.001 for all) and were considered high-risk complications. 65% of patients had no high-risk complications. One-year mortality for patients without high-risk complications was 4% compared with 28% for those with high-risk complications (P < 0.001). Conclusion: Unselected patients with STEMI treated with primary PCI have mortality rates corresponding to those reported in randomized clinical studies including transport of patients. Mortality is strongly related to high-risk complications developed during admission. Thus, patients with high-risk complications should receive special attention. The majority of patients (65%) without high-risk complications have an excellent short- and long-term prognosis following primary PCI.