BACKGROUND: We sought to evaluate the impact of initial electrocardiographic findings at presentation on in-hospital mortality and 30-day outcome of patients with acute coronary syndromes (ACS). METHODS: From October 2003 to September 2004, a sample of 6 hospitals located in several urban and rural Greek regions was selected, and almost all survivors 24 h after an admission for ACS were enrolled into the study (2172 patients were included in the study; 76% were men and 24% women). ECG and biochemical indices of myocardial damage were considered in all patients. Electrocardiographic findings at presentation were categorized as ST-elevation (STE), non-STE and non-diagnostic ECG abnormalities. RESULTS: Of the 2172 patients, 34% had STE, 24% had non-STE and the 32% of them had non-diagnostic ECG abnormalities. After adjusting for age, sex and various other risk factors we observed that patients with STE had 3.3 (95% CI 1.4 to 7.7) higher risk of dying during hospitalization compared to those who had non-diagnostic ECG abnormalities. Furthermore, patients with non-STE had 1.5 (95% CI 0.9 to 2.5) higher risk of having an event (death or re-hospitalization due to CVD) during the first 30-days following discharge as compared to those who had non-diagnostic ECG abnormalities. All patients presented with non-STE ACS had higher 30-day event rates. CONCLUSION: Patients with STE had higher in-hospital mortality, but lower longer term event rate after ACS in our population, irrespective of age, gender and other characteristics.