Residual stenosis, dissection and/or microvascular damage have been proposed as mechanisms of impaired flow after primary angioplasty (PCI) for acute myocardial infarction (MI). In this report we present a patient who underwent PCI for acute anterior MI. Coronary flow reserve (CFR) assessment performed after balloon dilatation suggested possible improvement of coronary flow after stenting. However, we did not observe any improvement in CFR just after stent implantation. We conclude that in patients treated with primary PCI the use of additional pharmacological treatment to prevent microcirculation injury during reperfusion and slow-flow or no-reflow phenomenon should be considered.