The plasma concentration of brain natriuretic peptide (BNP) measured 1 month after infarction in 74 patients with a first anterior infarction was significantly higher in patients with than without left ventricular (LV) remodeling, and showed a significant correlation with LV dilatation at follow-up. Progressive LV dilatation is accompanied by augmented BNP release from the left ventricle, and BNP concentration at I month may be a useful biochemical marker of maladaptive LV remodeling.