OBJECTIVE: To evaluate the impact of intraoperative transesophageal echocardiography on type-A acute aortic dissection. DESIGN: Retrospective observational study. SETTING: Tertiary care hospital. PARTICIPANTS: Sixty-four consecutive patients with type-A aortic dissection. INTERVENTIONS: Surgeons interviewed regarding how transesophageal echocardiography changed the surgical procedure. MEASUREMENTS AND MAIN RESULTS: Transesophageal echocardiography confirmed an ascending aorta intimal flap in 53 (83%) patients and an intramural hematoma in 9 (14%) patients. The aortic valve was bicuspid in 5 (8%) cases and a prior prosthetic valve was present in 4 (6%) patients. Aortic insufficiency was moderate in 12 (19%) cases and severe in 18 (28%) patients. Additionally, transesophageal echocardiography was useful in defining the size of pericardial effusion in 18 (28%) patients, 8 with large effusions and/or tamponade. Altogether, transesophageal echocardiography added data beyond prior imaging in 41 (64%) patients, including moderate or severe mitral regurgitation, right ventricular dysfunction, and atrial septal defects. The findings from intraoperative transesophageal echocardiography led directly to a change in planned surgery in 25 (39%) patients. Transesophageal echocardiography verified suitability of the repair in all cases of interposition graft or valve repair. CONCLUSIONS: Intraoperative transesophageal echocardiography provides incremental information to the original imaging examination in the management of type-A acute aortic dissection in nearly two-thirds of patients, leading to a change in the planned surgery in 39% of patients, thus supporting its role as suggested in recent guidelines.