The reductionofan effective orifice area is associated with the development of the phenomenon of prosthesis-patient mismatch (PPM). The purpose of this study was to evaluate the impact of PPM on the immediate results of surgical treatment in patients with aortic valve stenosis. The study included 50 patients who underwent aortic valve replacement. All patients were divided into 2 groups: with PPM (27 patients) and without it (23 patients). Immediate postoperative results were not statistically different. Analysis of echocardiographic data showed worse results in patients with PPM. It was marked reduction of LV EDV on 23.43±8.93 ml in the group without PPM and on 16.5±1.76 ml in patients with PPM (p<0.05). Also it was noted a greater decrease of pulmonary artery pressure (16.56±12.94 mm Hg) compared with the group with PPM (8.44±7.38 mm Hg), p<0.05. The presence of PPM in patients after aortic valve replacement leads to a slower reverse remodeling of the myocardium.