Endothelial progenitor cells (EPCs) play a key role in angiogenesis and vascular repair, although their exact functions are still disputable. The impact of EPC on left ventricular ejection fraction (LVEF) during acute myocardial infarction (MI) in patients treated with primary percutaneous coronary intervention (PCI) is also under investigation. The aim of this study was to assess the impact of different populations of EPC on LVEF during and 6 months after acute MI treated with primary PCI. The study included 34 patients with documented acute anterior wall MI. The control group consisted of 19 apparently healthy subjects. Blood for EPC assessments was obtained during the first 24 hours after MI and at 7 days and 6 months after PCI. CD34⁺/CD133⁺/CD45⁻, CD34⁺/CD31⁺/CD45⁻, CD34⁺/CD105⁺/CD45⁻, and CD31⁺/CD133⁺/CD45⁻ cell types were studied by flow cytometry. Echocardiography has been performed simultaneously with the EPC measurements. We observed a significant elevation of CD34⁺/CD133⁺/CD45⁻, CD34⁺/CD105⁺/CD45⁻, and CD31⁺/CD133⁺/CD45⁻ EPC at 7 days after PCI in comparison with 24 hours and 6 months after the MI. Patients with preserved LVEF at 7 days after PCI had also higher levels of CD31⁺/CD133⁺/CD45⁻. Acute anterior wall MI treated with primary PCI is followed by enhanced mobilization of EPC among which a high level of CD31⁺/CD133⁺/CD45⁻ subtype was strongly associated with the most preserved LVEF for up to 6 months after the index event. These data may provide some insight for future therapeutic strategies.