Intracoronary transfer of autologous bone marrow cells promotes recovery of left ventricular systolic function in patients with acute myocardial infarction. Although the exact mechanisms of stem cell therapy are still intensely debated, the concept of stem cell therapy has already been introduced into the clinical practice--at least as an adjunctive therapy in clinical trials. In this article the authors report their experiences about the first Hungarian phase I. trial in bone marrow stem cell transplantation after acute myocardial infarction. So far, four patients with acute ST elevation myocardial infarction were eligible and recruited into the trial. All patients received purified, autologous bone marrow stem cells into the re-opened infarct related artery via a second catheterisation. The primary end point of the study is ejection fraction, which is measured by cardiac MRI at the beginning and 6 months after recruitment. So far, cell transfer did not increase the risk of adverse clinical events or proarrhythmic effects.