This study was undertaken to evaluate the utility and efficacy of intraoperative transesophageal echocardiography (TEE) in the endovascular management of patients with acute type B aortic dissection. Twelve consecutive patients with acute type B aortic dissection underwent elective endoluminal stent-graft repair in the operating room under angiographic and TEE guidance. The follow-up protocol included spiral CT scanning before discharge from the hospital to assess thrombosis exclusion of the aortic false lumen, perfusion of branch vessels, and the absence of perigraft leak. No complications related to the use of TEE were encountered. TEE clearly demonstrated the presence and extent of the dissection flap in all patients. After the procedure a persistent perigraft leak or residual flow into the false lumen was diagnosed by TEE in 6 patients, whereas intraoperative angiography visualized only 3 cases. Postoperative CT scan confirmed these findings. One patient died 2 months later by aortic rupture secondary to a persistent perigraft leak not treated (8.3% mortality). No postoperative paraplegia or visceral ischaemia were registered, although an asymptomatic occlusion of left subclavian artery was observed. TEE monitoring detects perigraft leakage, identifies the entry tear, and accurately demonstrates sealing of the false lumen. TEE is essential in our practice as an adjuvant to fluoroscopy to achieve optimal results during endovascular stent-graft repair of acute thoracic aortic dissection.