During past 7 years, 43 patients less than 2 years of age underwent closure of the ventricular septal defect. Durations of postoperative use of a respirator were 3 days or less in 30 patients (short-period group) and over 3 days in remaining 13 patients (long-period group). There was no operative death. Pre-, intra- and postoperative factors affecting prolonged respiratory care were analyzed between two groups. Results were as follows: There were statistically significant differences between short- and long-period groups on age (9.7 versus 6.5 months), body weight (6.3 versus 5.2kg) at surgery, necessity of preoperative respiratory care on respirator (0/30 versus 4/13), duration of cardiopulmonary bypass (108 versus 132min.), aortic clamp time (56 versus 70min.) and respiratory index at the first postoperative day (1.1 versus 1.7). These results revealed the necessity of far earlier surgical intervention in symptomatic patients before respiratory distress develops. Furthermore, shorter cardiopulmonary bypass and aortic clamp times should always be in mind for attaining smooth postoperative course.