Autologous bone marrow mononuclear cells were transplanted by intracoronary infusion to patients with myocardial infarction after recovery of coronary perfusion. Controls received traditional therapy alone. Echocardiography was carried out before and 3 and 6 months after cell therapy. Cell transplantation did not appreciably improved left-ventricular contractility in comparison with the control group. In none patient cell therapy provoked malignant ventricular arrhythmias. Intracoronary infusion of bone marrow mononuclear cells in patients with myocardial infarction did not improve cardiac contractility and did not aggravate the course of the disease.