This series compromised 31 patients with pulmonary hypertension of 282 patients of ventricular septal defect(VSD) who underwent operation at the department of Thoracic and Cardiovascular Surgery in Chonnam University Hospital, from January, 1986 to December, 1991. Pulmonary hypertension was noted in 59 of 280 cases of VSD. Of them, 31 cases underwent cardiac catheterization on postoperative 8th to 77th month. Age at operation was ranged from 10 months to 29 years (mean 9.13 years). 17 patients were male and 14 patients were female. Results of follow-up studies were as follows: Cardiothoracic ratio was decreased from 0.59${pm}$0.04 to 0.54${pm}$0.03 (p=NS). Postoperative systolic pulmonary arterial pressure (PAPs), mean pulmonary arterial pressure (PAPm), and systolic right ventricular pressure (RVPs) were decreased significantly (p<0.001). And also Rp/Rs was decreased from 0.37${pm}$0.21 to 0.14${pm}$0.06 (p<0.02). However, systemic arterial pressure (SAP), right atrial pressure (RAP), and pulmonary capillary wedge pressure (PCWP) were changed insignificantly. There were significant relations of follow-up period with the decrement of PAP(p<0.005). In contrary, ther were no relations between the decrement of PAP and the age at operation. These data suggested that the long-term hemodynamic changes remained to be determined in some of the patients, even though they Were asymptomatic, with pulmonary hypertension.