Left ventricular dysfuction is common in immediate postoperative periods after surgical correction of heart diseases with chronic left ventricular volume overload. We speculated postoperative changes of left ventricular volume and unction in patients with patent ductus osus(PDA) who had underwent surgical repair at ages older than 16 years. Factors influencing postoperative left ventricular volume and function were also analyzed. Material and Method: From August 1989 to August 1999 thirty-siz adult patients with PDA 28 females and 8 males. were enrolled in this study. Their age ranged from 16 years to 57 years(mean :32 years). Types of surgical repair were division with primary closure in 22, division with patch closure in 6, internal obliteration using cardiopulmonary bypass in 4 and ligation in 4. Aortic clamping was combined during surgical repair in 22(61%) and cardiopulmonary bypass was used in 8(22%) Two-dimensional echocardiography studies were performed in 34(94%) preoperatively and in 25(66%) immediate postoperatively to assess postoperative changes of left ventricular internal dimensions. left ventricular volume and ejection fraction. Duration of postoperative follow-up ranged from 1 month to 99 months (mean:22 months) and 10 patients underwent 16 echocardiographic evaluation during this period Result : Preoperative and postoperative left ventricular systolic dimensions(LVIDs) were 42$pm$8.0mm and 42$pm$8.3mm left ventricular diastolic dimensions(LVIDd) were 64$pm$10.0mm and 56$pm$7.4mm left ventricular end systolic volumes(LVESV) were 62$pm$19cc (z=1.87$pm$0.06) and 59$pm$24cc(z=1.78$pm$0.08) left ventricular end diastolic volumes(LVEDL) were 169$pm$40cc(z-1.17$pm$0.1) and 112$pm$29cc(z=0.85$pm$0.1) and ejection fractions(EF) were 66$pm$6.7% and 48$pm$12.6% respectively. There were statistically significant differences between preoperative and postoperative values in LVDIDd(p=0.001) LVEDV(p=0.001) and EF(p=0.0001) while no significant difference is LVIDs and LVESV. Postoperative depression of ejcection fraction was significantly related with z-score of preoperative LVESV and LVEDV by univariateanalysis while LVEDV only was significant risk factor for postoperative LV dysfunction by multiple regressioin analysis ($Delta$LVEF=-13.3-4.62$ imes$LVEDV(z), p=0.001) During the follow-up periods ejection fractions become normalized in all except one patients. Conclusion ; Left ventricular function is usually deteriorated after the surgical correction of PDA in adult age and preoperative LVEDV is a major determinant of postoperative LV function.