N-terminal pro-B-type natriuretic peptide (NT-pro-BNP) is a predictor of left ventricular remodeling. Matrix metalloproteinases (MMPs) contribute to collagen breakdown that is associated with ventricular remodeling after acute myocardial infarction (AMI). We assessed the association between circulating levels of NT-pro-BNP, MMP-2, and MMP-9 and their inhibitor (tissue inhibitor of metalloproteinase-1) early (24 and 72 hours) and late (7 and 30 days) after AMI in 108 patients who had ST-elevation AMI (90 men; mean age 60 years). Serum MMP-2 levels measured 24 and 72 hours after AMI were inversely associated with NT-pro-BNP levels, whereas MMP-9 serum levels were positively related. During late-stage remodeling after AMI, circulating concentrations of tissue inhibitor of metalloproteinase-1 were independently associated with NT-pro-BNP levels 7 and 30 days after AMI. This study shows that, in patients who have ST-elevation AMI, circulating levels of NT-pro-BNP are associated with MMPs in a species-specific and time-dependent manner.