Most patients with Marfan's syndrome have cardiovascular manifestations and complications of these abnormalities lead to death in 50% of patients by the age of 32. This report is concerned with the performance of 79 operations to control these problems in 41 patients during a 16-year period. There were 3 early deaths and 11 late deaths, with survival at 15 years in 62%. The cardiovascular manifestations assumed eight patterns of involvement, in brief, consisting of aneurysms of ascending aorta, mitral valve insufficiency, aortic dissection and dissecting aortic aneurysm, and degenerative distal fusiform aortic aneurysm. These lesions occurred in isolated form or in association with others, hence the larger number of patterns of involvement. Various methods were employed in treatment of aneurysms of the ascending aorta, which was associated with aortic valvular insufficiency in most. The most reliable method of controlling disease at this level was composite valve graft replacement of fusiform aneurysms and separate valve graft operation for dissections occurring in the previously uninvolved aorta. Isolated mitral valve insufficiency was relieved by standard mitral valve replacement and this operation could be safely combined with composite valve graft replacement of the ascending aorta. More distant aneurysms of the aorta, either degenerative or chronic dissections, were susceptible to reconstruction as employed in the nonMarfan patient. Treatment of multiple lesions was staged, treating the more symptomatic condition first. Regular follow-up examination is important in these patients to detect new lesions and to evaluate known lesions. An aggressive approach is suggested in their treatment because 63% of the 11 late deaths in this series were due to lesions that could be successfully treated by presently available methods.