Background: Surgical replacement of aortic arch aneurysms (AA) is technically difficult, and carries a significant operative risk. Timing of surgical intervention in asymptomatic AA is a complex problem, and the benefits of prophylactic replacement of AA remains unclear. We tried to compare long-term results of early prophylactic surgery to medical follow-up in asymptomatic AA. Methods: From 1997 to 2005, we prospectively included a total of 60 consecutive patients (45 men, age; 61짹12 yrs) with AA incidentally detected on imaging studies. Isolated AA was documented in 17 patients, and AA also involved ascending aorta in 18 patients, and descending aorta in 25 patients. The maximal size of AA was measured on axial computed tomography images, and the mean diameter of AA was 63짹13 mm. Results: Early prophylactic surgery was performed on 35 patients (OP group), and medical management with serial imaging follow-up was performed on 25 patients (MED group). There were no significant differences between the two groups in terms of age, gender, and the size and extent of AA. During follow-up of 47짹28 months, 1 operative death and 4 AA-related deaths occurred in the OP group, and there were 9 AA-related deaths in the MED group (p=0.05). In MED group, there were 10 cases of late AA surgery due to significant changes in the size of AA or development of symptoms during follow-up. The 5-year actuarial survival rate was significantly higher in the OP group (84짹8%) than in the MED group (56짹12%, p<0.05) (figure). Conclusions: Recent advances in surgical technique significantly decreased the operative risk of AA, and early prophylactic replacement can be recommended in asymptomatic AA at a diameter of > 60 mm.