BACKGROUND Recent years have witnessed the increasing role of NT-proBNP as a prognostic tool in acute coronary syndrome (ACS). OBJECTIVE To evaluate prognosis of patients over 65 years of age with acute myocardial infarction (MI), based on NT-proBNP levels measured in the acute phase of MI. METHODS The study involved 161 patients aged 79+/-8 hospitalised with acute MI, either with or without ST segment elevation (STEMI/NSTEMI). The NT-proBNP levels in serum were measured and echocardiography with left ventricular ejection fraction (LVEF) was performed in all patients upon admission to hospital. These tests were repeated after six months with the patients additionally subjected to the 6-minute walk test (6MWT). RESULTS The average NT-proBNP level in the studied patients at admission to hospital was 7058+/-9649 pg/ml and increased in proportion to the age of patients. The NT-proBNP level did not differ significantly in STEMI and NSTEMI patients. Fifty-three patients died during the 6-month follow-up period. Their NT-proBNP levels at admission were significantly higher than in patients who were alive at the end of follow-up: 12237+/-13035 pg/ml compared with 4606+/-6214 pg/ml (p=0.0001). The NT-proBNP level upon admission to hospital proved to be an independent predictor of death in the six-month period following MI. Six months after MI the average left ventricular ejection fraction in the studied group of patients was 49+/-10% and the average distance in the 6MWT was 361+/-151 m. There was a significant negative correlation between these two parameters and the initial NT-proBNP level determined upon admission to hospital. CONCLUSIONS An increased NT-pro-BNP level, measured in the acute phase of MI, is a significant prognostic factor during six-month follow-up after MI in patients aged over 65.