Aim To study possible correlations between echocardiography (EchoCG) indexes and markers of myocardial fibrosis, procollagen I C-terminal propeptide (PICP) and procollagen III N-terminal propeptide (PIIINP) during one year following ST-segment elevation myocardial infarction (STEMI).Material and methods 120 patients with STEMI were evaluated. EchoCG was used to assess dimensions and volumes of heart chambers, left ventricular (LV) systolic function, mean pulmonary arterial pressure (mPAP), and indexes of LV diastolic function (Em, early diastolic lateral mitral annular velocity; e’, peak early diastolic septal mitral annular velocity; E / e’, ratio of peak early diastolic transmitral inflow velocity and mitral annular velocity -, Е / А, ratio of peak early and late transmitral inflow velocities; DT, deceleration time of LV early diastolic filling). EchoCG indexes and serum concentrations of PICP and PIIINP were determined at 1 (point 1) and 12 (point 2) days of disease and one year after STEMI (point 3). The sample was divided into two groups: group 1 (n=86; 71.7 %) included patients with a LV ejection fraction (EF) ≥50 % and group 2 (n=34; 28.3 %) consisted of patients with LV EF ≤49 %.Results At one year, the number of patients with signs of diastolic dysfunction increased by 10% in group 1 whereas myocardial systolic dysfunction worsened in both groups. LV EF decreased in 15 (17.4%) patients of group 1 and in 4 (11.8%) patients of group 2. Concentrations of PIIINP were correlated with Em, E / e’, mPAP, PICP, e’, and LV EF.Conclusion Direct correlations between PIIINP concentrations and Em, E / e’, and mPAP were found in the group with LV EF ≥50 %. In the group with LV EF <50 %, correlations were observed between PICP concentrations, LV EF, and e’. Also, in this group, the increase in PIIINP was statistically more significant. These results indicate continuing formation of myocardial fibrosis in a year following MI, which may underlie progression of chronic heart failure.