Since January 1977 to the end of September 1982, total 60 Ionescu-Shiley pericardial xenograft heart valves were implanted for valve replacement in 50 patients at the Han Yang University Hospital. The operative procedures were as follow: Mitral valve replacement [MVR] in 25 patients, Mitral valve replacement [MVR] and Tricuspid valve [TV] annuloplasty in 7 patients, Aortic valve replacement [AVR] in 8 patients, Aortic valve replacement [AVR] and Mitral valve replacement [MVR] in 8 patients. Aortic valve replacement [AVR] and Mitral valve replacement [MVR] and Tricuspid valve [TV] annuloplasty in 2 patients. To evaluate the immediate hemodynamic changes after valve replacements, the pressures of each cardiac chamber and ulmonary artery were checked before and after valve replacement on the operation table. Right ventricle [RV] pressure was decreased from 52.09ulcorner6.71 to 45.57ulcorner5.03 mmHg, Pulmonary artery [PA] pressure was decreased from 45.97ulcorner2.69 to 41.00ulcorner3.99 mmHg, and Left atrium [LA] pressure was decreased from 30.33ulcorner13.02 to 22.76ulcorner.97 mmHg before and after valve replacement. In MVR group, RV pressure was decreased from 49.17ulcorner7.89 to 43.14ulcorner4.14 mmHg, PA pressure was decreased from 44.67ulcorner3.18 to 38.67ulcorner2.85 mmHg, and LA pressure was decreased from 31.46ulcorner13.47 to 21.91ulcorner.17 mmHg. In AVR group, RV pressure was decreased from 53.0ulcorner7.44 to 44.71 ulcorner3.24 mmHg, PA pressure was decreased from 34.83ulcorner0.73 to 31.86ulcorner.36 mmHg, and LA pressure was not changed. In double valve replacement [MVR and AVR] group, RV pressure was decreased from 57.50ulcorner3.82 to 42.50ulcorner.80 mmHg, PA pressure was decreased from 51.17ulcorner1.42 to 43.33ulcorner4.53mmHig, and LA pressure was decreased from 34.33ulcorner2.09 to 25.50ulcorner0.21 mmHg. But in the group where MVR and TV annuloplasty were performed, preoperative RV and PA pressure were markedly increased and no pressure decrease in RV and PA noticed after valve replacement. This study shows good immediate postoperative hemodynamic results after valve replacement using Ionescu-Shiley xenograft valve except in the cases of MVR and TV annuloplasty and advanced disease with pulmonary hypertension.