A clinical study was performed on 164 cases of PDA experienced at the Dept. of Thoracic and Cardiovascular Surgery of Pusan National University Hospital during 6 years from Jan. 1981 to Dec. 1986. It was shown that the PDA was a female-dominant heart disease [male to female ratio, 1:2.8] and two most common symptoms were frequent URI [45.6%] and exertional dyspnea [36.7%]. Continuous machinery murmurs were detected in 143 cases [87.2%], increased pulmonary vascularities [89.0%] and cardiomegalies [63.4%] by chest X-ray. The signs of LVH [43.9%], RVH [3.7%] and BVH [4.9%] were noted on the EKG. Cardiac catheterizations were performed on 67 out of 164 patients and the mean systolic pulmonary artery pressure was 48mmHg [range: 18-131mmHg] and the mean Qp/Qs was 3.1 [range:1.2-8.5] and Rp/Rs below 0.25 was 83.6%. Associated cardiac anomalies were VSD [7.9%], ASD [3.0%], pulmonary valvular stenosis [2.4%] and left persistent SVC [2.4%]. Operative methods were as follows; ligations [145; 88.4%] and divisions [6;3.7%] were performed through the left posterolateral thoracotomies without mortality and the remained cases [13;8.0%] were managed under the cardiopulmonary bypass because of the associated cardiac anomalies. Atelectasis [4.9%] and pneumonia [4.3%] were most frequent postoperative complications and the overall mortality rate was 2.4% [4 out of 164 cases].