Adverse effects of cardiopulmonary bypass on blood and lungs are encountered more severelyin pulmonary hypertensive patients undergoing mitral valve surgery. Aim of this study is to identify the favorable effects of conventional ultrafiltration on postoperative pulmonary functions, hemodynamics, morbidity or mortality in pulmonary hypertensive patients undergoing mitral valve surgery. 40 patients with severe pulmonary hypertension who underwent mitral valve surgery were included in study. Patients were divided into two groups according to whether conventional ultrafiltration was applied or not. Demographic data, preoperative transthoracic echocardiography, respiratory functions, complete blood count, biochemical parameters, alterations in pulmonary functions, bleeding, use of inotropic agents and blood products, intubation time, mortality, morbidity, length of intensive care unit and hospital stay, were evaluated. Intubation time (7.97±2.77 vs. 10.12±2.95; p<0.05), intensive care stay (42.20±65.99 vs. 44.25±14.13; p<0.05), hospital stay (7.20±1.13 vs. 10.12±3.27; p<0.05), bleeding (370.00±216.28 vs. 506.25±247.03; p<0.05) were significantly shorter in study group. Use of blood products (4.20±1.23 vs. 4.90±2.13; p>0.05) and inotropic agents (14 vs. 18; p>0.05) were less than the control group. Increase of pulmonary compliance, cardiac index, oxygen index, decrease of alveolar-arterial oxygen pressure difference and ventilation index were significant in both groups. Hematocrit (28.07±3.18 vs. 26.96±2.51; p>0.05) and white blood cell (13.56±2.37 vs. 13.03±2.51; p>0.05) were higher in the study. No morbidity and mortality were presentin both groups. Conventional ultrafiltration decreased the intubation time, intensive care unit stay, hospital stay, bleeding, use of blood products and inotropic agents. Favorable effects were also detected on pulmonary compliance, cardiac index, oxygen index, alveolar-arterial oxygen pressure difference and ventilation index. Studies with larger patient population, application of conventional and modified ultrafiltration together may give significant results for pulmonary functions.