A patient with unilateral diaphragmatic paralysis (UDP) after cardiac surgery, commonly extubated without any troubles, encounters a serious fetal respiratory complication in a rare case. We had a case of a 68-year-old man under long term mechanical ventilation (MV) because of UDP and phrenic nerve injuries after the replacement of the ascending aorta. After this operation he suffered from mediastinal infection and needed MV for a few days. Thereafter, he was extubated successfully and returned to the ward, but his chest X-p showed right diaphragmatic elevation. Two days after returning to the ward, he developed dyspnea and tachypnea and received MV for two months. We decided to perform diaphragmatic plication (DP) because of long term MV and difficulty in respiratory weaning. The patient was successfully weaned from MV on the 4th postoperative day of the right DP. Pulmonary function test was improved dramatically. In a case of long term MV due to UDP, DP can be one of effective treatments.