The clinical and hemodynamic characteristics, perioperative and early postoperative results were studied in 38 patients with aortic valve prosthesis in order to determine the indications for surgical treatment in isolated aortic valvular disease. The basic factors determining the need for surgical treatment are: severity of the aortic lesion--stenosis and/or incompetence, degree of the harmful action of the aortic valvular disease on the left ventricle (clinical data for left ventricular failure; hypertrophy and dilatation--telediastolic volume greater than 300 ml/m2, telesystolic volume greater than or equal to 50 ml/m2; myocardial lesion; hemodynamic data for left ventricular dysfunction) and functional class of the patients. Most of the patients were with severe aortic incompetence and/or aortic stenosis and considerably diminished functional capacity. Only few patients had a low degree valvular lesion but they also showed some of the signs of its harmful action on the left ventricle.