To investigate the relationship between natriuretic peptides and left ventricular remodeling after acute myocardial infarction, left ventriculography and blood sampling were performed on admission, after 1 month and after 3 months in 33 patients with acute myocardial infarction (15 anterior and 18 inferior). Plasma atrial and brain natriuretic peptide concentrations at 1 and 3 months were higher than those of controls (P<0.01). Brain natriuretic peptide concentrations correlated with changes in left ventricular end-diastolic volume index after 1 and 3 months (1 month: r=0.57, P=0.003; 3 months: r=0.47, P=0.006). Atrial natriuretic peptide concentrations also correlated with changes in left ventricular end-diastolic volume index after 1 and 3 months (1 month: r=0.40, P=0.02; 3 months: r=0.61, P<0.001). Our results indicate that natriuretic peptide concentrations increase in the chronic phase of acute myocardial infarction and may relate to left ventricular remodeling. Thus, atrial natriuretic peptide as well as brain natriuretic peptide concentrations may be useful biochemical markers in identifying asymptomatic patients at risk for heart failure or sudden death after acute myocardial infarction.