Objective of this study is to evaluate influence of acute aortic dissection on long-term results of aortic root reconstruction in patients with Marfan's syndrome. 19 patients who underwent consecutive aortic root reconstruction between 1985 May to 1998 February were retrospectively reviewed. Patients who associated acute aortic dissection at the time of operation (group D, n = 7) were compared long-term results with those who did not (group non-D, n = 12). Mean follow-up period was 5.1 +/- 3.2 years and longest follow-up term was 12.5 years. In each group early postoperative death was found in one patient. In-hospital mortality in each group were respectively; 14.2% and 8.3%. Late deaths were found in four patients who all belonged to group D, respectively caused by; rupture of thoracoabdominal aneurysm, DIC after subsequent thoracoabdominal surgery, sepsis due to prosthetic valve endocarditis, and sudden death. Actuarial overall survival rate including operative death in D and non-D group were respectively; 0.0 +/- 0% at 6.6 years and 91.1 +/- 8.0% at 12 years. Overall cumulative survival rate was 56.6 +/- 14.0%. Freedom from cardiovascular events, in D and non-D group were respectively; 0.0 +/- 0% at 6.6 years and 60.0 +/- 25.3%, and freedom free form dilatation of residual aorta were respectively; 0.0 +/- 0% at 6.6 years and 100.0 +/- 0% at 12 years. Freedom from subsequent cardiovascular surgery in group D, group non-D and over-all patients were respectively; 0.0 +/- 0% at 6.6 years, 60.0 +/- 25.3% at 12 years and 42.6 +/- 20.2%. In this study, acute aortic dissection in Marfan's syndrome significantly increased late cardiovascular events including dilatation of residual aorta, subsequent aortic surgery and late mortality. On the other hand, excellent long-term results after aortic root reconstruction were found in non-dissection Marfan's syndrome. Considering high incidence of late dilatation of residual aorta, simultaneous total arch replacement with aortic root reconstruction is recommended in acute dissecting Marfan's syndrome. Whereas, preventive simultaneous arch replacement is not required in non-dissecting Marfan's syndrome because of less postoperative vascular events.