Patent ductus arteriosus in adult is frequently complicated with aneurysm, calcification and pulmonary hypertension. Therefore, surgical treatment of patent ductus arteriosus in adult has some differences from that of infants and children. We have experienced 25 cases of adult patent ductus arteriosus from July 1983 to December 1994. Mean age of the patients was 26.6 years[16-59 years . There were 12 males and 13 females. Exertional dyspnea was the most frequent clinical manifestation. Pulmonary hypertension was present in eight patients. Ligation was done in 20 cases and surgery using cardiopulmonary bypass was done in 5 cases. There was one hospital death, which had a 5x5cm sized main pulmonary artery aneurysm and was operated under cardiopulmonary bypass. Recanalization occured in one patient who received Teflon-felt supported ligation. Although one case of recannalization after ligation was present, we believed the fact that ligation was safe and simple method of operation in adult patent ductus arteriosus without calcification and aneurysm.