This study evaluated the relevance of our indication of aortic root operations for acute type A aortic dissection and compared early and long-term outcomes of emergency type A aortic dissection operations between patients who underwent aortic root operations and those who did not.We retrospectively reviewed 316 consecutive patients who underwent emergency aortic operations for acute type A aortic dissection between January 2009 and September 2013. We performed simultaneous aortic root operations when the aortic root diameter was greater than 45 mm or an intimal tear was present in the aortic root, or both. After this indication, we performed aortic repair involving the aortic root in 40 patients (aortic root replacement [ARR] group, 12.7%) and not involving the aortic root in 276 patients (non-ARR group, 87.3%). We analyzed early and long-term outcomes, including late aortic root events.In-hospital mortality was 12.5% (5 of 40) in the ARR group and 4.7% (13 of 276) in non-ARR group (p = 0.05). Overall survival at 3 and 5 years was 84.8% and 84.8%, respectively in ARR group and was 91.9% and 91.9%, respectively, in the non-ARR group (p = 0.078). Late aortic root events, defined as aortic root dilatation (≥3 mm/y), reoperation of the aortic root, aortic regurgitation (moderate or higher), and pseudoaneurysm, were observed in no patients in the ARR group and in 32 patients (11.6%) in the non-ARR group (p = 0.029). In the non-AAR group, dissection of 2 or more aortic sinuses was the only independent predictor of a late aortic root event (hazard ratio, 2.20; 95% confidence interval, 1.08 to 4.61; p = 0.03).Simultaneous aortic root operations significantly reduced the incidence of late aortic root events. The dissection of 2 or more sinuses of Valsalva was associated with a late aortic root event in patients who did not undergo aortic root operations.