Recent reports on stem cell transplantation -an innovative approach to repair damaged myocardium following acute myocardial infarction (MI)- have raised the question of a possible spontaneous mobilization of corresponding stem cells from the bone marrow of ischemic patients (pts). Exposed to vascular endothelial-derived growth factor (VEGF) such cells would differentiate into myocardial cells within the infarcting myocardium, thus hopefully initiating the reparative process. The present work is performed on 21 patients with acute MI in order to assess the prevalence in the peripheral blood of marrow derived stem cells expressed in term of CD34 using flow cytometric analysis, as well as the serum level of VEGF using an enzyme immunoassay (EIA). Both the CD34+ cells and the VEGF were quantitatively studied in relation to the hospital course of acute myocardial infarction e.g. on the admission day, the 3rd day after the onset of the infarction and the predischarge day (5th-7th days). The CD34+ cells were insignificantly different along the hospital course. The serum VEGF showed a trend towards decrease rather than increase. The correlative studies in AMI group showed a significant negative correlation between TLC and VEGF on day 3 and predischarge day. Although statistically insignificant, CD34 population was positively correlated with the myocardial damage expressed in terms of peak CK.