We had operated 5 cases of residual ventricular septal defect after primary repair of isolated ventricular septal defect from 1975 to 1981. Three were male and two were female. Their ages ranged from 7 to 25 years old. In 4 cases previous patch was detached and one case had left ventricular - right atrium communication. They had had residual symptoms after primary operation and chest x-ray showed cardiomegaly. Cardiac catheterization was performed in all cases. Residual left to right shunt was more than 1.4: 1 with pulmonary hypertension. Their postoperative course were uneventful and long term follow up revealed that they were good health until one to 4 years. [KTCS 1982;3:316-320]