BACKGROUND Intravenous thrombolytic therapy is the standard care for patients with acute myocardial infarction, based upon its widespread availability and ability to reduce patient mortality well demonstrated in randomised trials. Despite its proven efficacy, thrombolytic therapy has limitations. Many patients are ineligible for treatment with thrombolytics. Of those given thrombolytic therapy, 10 to 15 percent have persistent occlusion or reocclusion of the infarct-related artery. Consequently, primary angioplasty (primary PTCA) has been advocated as a better treatment of myocardial infarction. OBJECTIVE To determine whether primary coronary angioplasty is superior to thrombolytic therapy for the treatment of patients with acute myocardial infarction. METHODS Electronic search of The Cochrane Library (1998; Issue 2). MEDLINE (to January 1998); references from reviews, trials and previously published meta-analyses; and experts. Date of most recent searches January 1998. METHODS All unconfounded, randomised controlled trials comparing primary angioplasty against intravenous thrombolysis in patients with acute myocardial infarction METHODS At least two independent reviewers abstracted data on morbidity and mortality and trial characteristics. The following outcomes were assessed: total mortality at the end of the study, reinfarction, stroke of any type, composite endpoint of death and reinfarction, recurrent ischemia, severe bleeding and coronary artery bypass grafting. RESULTS Ten trials including 2573 subjects were identified. Compared to thrombolytic therapy, primary angioplasty was associated with a significant reduction in short-term mortality at the end of the studies (relative reduction in risk RRR = 32% 95%CI = 5%;50%). Similar reductions were observed for the rate of reinfarction (RRR = 52%, 95%CI = 30%;67%), recurrent ischemia (RRR = 54%; 95%CI = 39%,66%) and for the combined criteria death or reinfarction (RRR = 46%; 95%CI=30%;58%). The frequency of strokes of any cause was significantly decreased by 66% (95%CI=28%;84%). No significant difference was observed for the incidence of major bleeding (relative risk RR =1.18, 95%CI = 0.73;1.90) but the confidence interval was large. The superiority of the primary angioplasty over thrombolysis in terms of the composite endpoint (mortality and reinfarction) was less with accelerated t-PA (RR=0.70, 95%CI=0.51;0.97) than with streptokinase (RR=0.30, 95%CI=0.17;0.53). The biggest and most recent trial, Gusto 2B (GUSTO-2B 97), which involved general as well as highly specialised centres, obtained less favorable results. CONCLUSIONS This meta-analysis suggests that angioplasty provides a short-term clinical advantage over thrombolysis which may not be sustained. Primary angioplasty when available promptly at experienced centres, may be considered the preferred strategy for myocardial reperfusion. In most situations, however, optimal thrombolytic therapy should still be regarded as an excellent reperfusion strategy.