The purpose of this study was to investigate the long-term sequential changes in serum levels of the carboxyterminal propeptide of type-I procollagen (s-PICP), which is a marker of type-I collagen synthesis, and to assess its clinical value in relation to left ventricular (LV) function and prognosis following acute myocardial infarction (AMI). Forty-eight consecutive patients with their first AMI and 15 control subjects were studied. Patients with AMI were stratified according to the changes in s-PICP levels between days 1 and 90 (ΔPICP) and divided into group I with ≤16.0 µg/l or group II with >16.0 µg/l. Patients in group II were characterized by LV dilatation, no improvement in ejection fraction and development of impaired diastolic filling from day 1 to 360, findings which were in contrast to group I. Cox regression analysis identified changes in s-PICP of >16.0 µg/l as an independent predictor of cardiac death or heart failure during follow-up. In conclusion, ΔPICP relates to long-term changes in LV function and size, and provides prognostic information following AMI.