The aim of this study was to assess the comparative diagnostic value of transesophageal echocardiography (TEE) and retrograde aortography for morphologic evaluation and anatomic mapping of aortic dissection. Seventy patients (aged 18 to 79 years) were prospectively evaluated with both techniques for suspected aortic dissection. In 64 patients, findings on aortography and TEE could be validated against intraoperative (n = 53) and postmortem (n = 11) findings. Examination time was significantly shorter for TEE (9 +/- 6 vs 48 +/- 25 minutes; p < 0.001). For the detection of aortic dissection, aortography showed lower sensitivity (87.5% vs 97.5%) and negative predictive value (85.3% vs 96.7%; both trends did not reach statistical significance) due mostly to the inability to identify noncommunicating dissection (dissection without intimal tears). For the epiphenomena of aortic dissection, aortography was significantly more accurate (97.2% vs 78%; p < 0.05) in assessing the site of entry, and TEE was more accurate in identifying thrombus formation (90% vs 65%; p < 0.05). There was no significant difference between aortography and TEE with regard to assessing secondary tears, aortic regurgitation, coronary dissection, and extension of the dissection. Thus, both TEE and aortography offer detailed anatomic mapping for guided surgical interventions. In elective patients, integration of both techniques seems the best approach; in unstable patients, TEE may be preferential because it is less invasive, requires no contrast injection, and provides accurate diagnosis in a short time at the bedside.