Background: The outcomes of reduction ascending aortoplasty (RAA) performed with aortic valve surgery were evaluated and the results of RAA in patients with bicuspid aortic valve (BAV) were compared with those in patients with tricuspid valve. Methods and Results: From October 1994 to April 2009, 88 patients underwent RAA. Aortic valve was bicuspid in 45 patients (BAV group) and tricuspid in 43 patients (TAV group). Total circulatory arrest was required in 45 patients. Preoperative ascending aortic diameter was 45.5±4.7mm. Early mortality rate was 1.1%. Ten-year survival rate and freedom from cardiac death were 91.1% and 96.2%, respectively. No differences in clinical outcomes were found between the 2 groups. No aorta-related complications including aortic rupture, dissection and reoperation were observed. Aortic diameter at the last follow-up (61±43 months) was 37.8±4.3mm. The interval between surgery and follow-up CTA was associated with aneurysmal recurrence (P=0.022). Average rate of dilatation was 0.42±0.49mm/year (n=37). A need for total circulatory arrest was associated with an increase of the aortic diameter (P=0.009). BAV was associated with neither aneurysmal recurrence nor increase of aortic diameter. Conclusions: RAA in patients with an ascending aortic aneurysm combined with aortic valve disease could be performed with acceptable early and long-term outcomes, even in patients with BAV. Long-term follow-up evaluation might be necessary due to the risk of redilatation especially in patients with an extended aneurysm, which required total circulatory arrest for RAA. (Circ J 2011; 75: 322-328)