The operative management of aneurysms of the ascending aorta continues to present a technical challenge to the surgeon, and the results obtained provide a useful clinical assessment of the means of myocardial protection. We present a series of 35 consecutive patients who underwent operations for aneurysms of the ascending aorta during which myocardial protection was achieved with hypothermia and potassium cardioplegia. Twenty-three patients underwent aortic valve replacement and resection and grafting of a chronic ascending aortic aneurysm. Aortic valve replacement and aneurysmorrhaphy of a chronic ascending aneurysm were performed in five patients. Four patients underwent resection and grafting of a chronic ascending aortic aneurysm and three patients resection and grafting of acute aortic aneurysms. Aortic cross-clamp times varied from 48 minutes to 2 hours, 32 minutes, with a mean cross-clamp time of 1 hour, 29 minutes. There was one death in the hospital in this series of 35 patients for a mortality rate of 2.8%. Of the 34 survivors, there has been one late death from recurrent sternal wound infection. This clinical series documents the efficacy and safety of hypothermic potassium cardioplegia for protection of the myocardium during extended periods of ischemia attending operative correction of ascending aortic aneurysms.