Despite high efficacy of percutaneous coronary intervention (PCI), in-stent restenosis proves to be a significant problem of therapy. Restenosis concerns around 30 percent of patients. Studies have suggested that restenosis is initiated by cells which participate in intense inflammatory reaction caused by stent implantation. Atherosclerotic plaque rupture during stent implantation and PCI-associated injury of the vessel wall lead to hemorrhage and release of various cytokines. They are probably responsible for quick recurrence of vascular lumen stenosis (restenosis). Interleukin-6 (IL-6) is known as a main pro-inflammatory cytokine, whereas Transformig Growth Factor-beta1 (TGF-beta1) has anti-inflammatory properties. The study population comprised 36 patients with myocardial infarction treated with PCI with stent implantation. They underwent control coronary angiography after 12 months. At this time plasma concentration of IL-6 and TGF-beta was measured in peripheral blood. Serum IL-6 concentration in the analyzed population correlates with lumen loss (p<0.01) and the severity of stenosis (p<0.001). No such correlation was found between serum TGF-beta1 concentration and lumen loss (p=NS) or the severity of stenosis (p=NS). The IL-6 plasma concentration may be a marker of in-stent restenosis in patients after PTCA, while the concentration of TGF-beta1 is not associated with the occurrence of restenosis at one year of follow-up.