This study retrospectively reviews the hospital records of 24 patients who developed ascending aortic dissection during or following 6,943 cardiac surgical procedures performed from January, 1971, through December, 1981. Group I consists of 15 patients with ascending aortic dissection presenting intraoperatively during myocardial revascularization. Group II consists of nine patients, seven who underwent myocardial revascularization and two who underwent aortic valve replacement, who developed ascending aortic dissection 30 minutes to 21 days after cardiac operation. Four of these patients had poorly controlled hypertension postoperatively. Surgical repair was attempted in all patients in Group I, with an operative mortality of 33%. The major cause of death was myocardial dysfunction secondary to ischemia. There were no operative deaths among six patients managed with closed plication techniques alone. Four of nine patients in Group II underwent ascending aortic dissection repair with an operative mortality of 50%. The overall mortality in Group II was 78%. The major factor in this high mortality was a delay in diagnosis and surgical therapy. Early diagnosis of the intraoperative or postoperative ascending aortic dissection process is essential to minimize the extent of dissection and prevent delay of definitive surgical therapy. Closed aortic plication of the intimal injury rather than more extensive aortic repair may reduce morbidity and mortality in selected patients.