BACKGROUND: There are only few data on long-term effectiveness of the stem cell therapy. AIM: We studied the time course of global and regional left ventricular function in patients with acute myocardial infarction within 1 year after the autologous mononuclear bone marrow cell transplantation. METHODS: Sixty patients with a first acute myocardial infarction, who had been randomized into 3 groups, completed a 12-month protocol. Two groups were intracoronarily given bone marrow cells in either higher (10(8) cells, HD group, n=20) or lower (10(7) cells, LD group, n=20) doses. Twenty patients without cell transplantation served as a control (C) group. Doppler tissue imaging and the gated technetium-99m sestamibi single photon emission computed tomography were performed before cell transplantation and at 3, 6, and 12 months later. RESULTS: The baseline peak systolic velocities of longitudinal contraction of the infarcted wall (S(infarct)) of 5.2 cm/s, 4.6 cm/s, and 4.4 cm/s in C, LD, and HD groups increased by 0.0 cm/s, 0.3 cm/s (p=NS vs. C group), and by 0.7 cm/s (p<0.05 vs. C group), respectively, at 3 months. At 12 months, however, the corresponding changes from baseline values of 0.1 cm/s, 0.2 cm/s, and 0.6 cm/s did not differ significantly (all p=NS). In contrast, the post-transplant improvements in the left ventricular ejection fraction by 6%, 7%, and 7% at months 3, 6, and 12, respectively, were preserved in HD group patients during the whole 12-month follow-up and remained significantly better as compared to controls. CONCLUSIONS: In our study, the autologous mononuclear bone marrow cell transplantation provided sustained improvement in global left ventricular systolic function in patients with acute myocardial infarction. However, when evaluating regional systolic function of the infarcted wall, the short-term benefit was partially lost during the 12-month follow-up.