Aims: The diagnostic and prognostic capacity of biochemical markers of acute myocardial infarction in the emergency department were evaluated in consecutive patients (n = 155) with suspected acute myocardial infarction. Methods and Results: Serum myoglobin ≥ 110 μg.l-1 and creatine kinase MB(mass) ≥ 5 μg.l-1 had a high accuracy (0.77-0.85) (ns) for acute myocardial infarction diagnosis in patients presenting > 2 h after symptom onset. Troponin-T (≥ 0.10 μg.l-1) had a lower accuracy (0.53-0.70) for acute myocardial infarction diagnosis, but was the most important 1-year prognostic marker (cardiac death or non-fatal acute myocardial infarction). In patients without ST elevation, combined analysis of two biochemical tests would accurately identify an additional 20% of acute myocardial infarction patients (predictive value of a positive test = 0.82) and also identify those without acute myocardial infarction (predictive value of a negative test = 0.80). One-year event-free survival was excellent (96%) for patients with two negative biochemical tests, intermediate (74%) for those with discordant tests, and only 53% for patients with two positive biochemical tests. Conclusion: Analysis of biochemical tests in the emergency department prior to hospital admission could accurately identify approximately 20% additional acute myocardial infarction patients. The prognosis of these patients is poor, and they may be a target for primary PTCA or new early initiated aggressive medical therapies. (C) 2000 The European Society of Cardiology.