Of 255 patients undergoing closure of ventricular septal defect (VSD), 48% were younger than 2 years, 59% had associated cardiac and 26% non-cardiac abnormality, 13% had multiple, and only 29% isolated VSD. VSD was closed via the left ventricular apex in seven cases, without increased morbidity or mortality. The three early and six late deaths occurred in patients with complicated defects. Pulmonary vascular occlusive disease caused four deaths (1 early, 3 late). At follow-up (mean c. 3, range 1-11 years), 79% of the patients were well, 10% had cardiac symptoms and 7.5% had symptoms from associated noncardiac anomalies. Reoperation for significant residual VSD was required in 12 cases (4 single and 8 multiple VSD). Complete, pacemaker-requiring A-V block was found in four patients (none with simple VSD closure). It is concluded that 1) concomitant cardiac and non-cardiac lesions are common in VSD, 2) mortality is closely related to such lesions and to pulmonary vascular occlusive disease, 3) the latter is a rare, but real cause of death, 4) left ventricular approach need not increase mortality or morbidity, 5) significant residual VSD is rare after single, but common in multiple VSD, and 6) risk of complete A-V block after simple VSD closure is very low.