A case of acute aortic dissection without intimal tear is reported. A 68-year-old woman with acute onset of Stanford type-B aortic dissection was admitted. Because of progressive anemia and pleural leakage, an operation was performed. False lumen of the descending thoracic aorta was occupied with fresh hematoma, but no sign of an intimal defect was found. Although aortic dissection without intimal tear has been reported via angiography, CT scan, MRI, and autopsy, surgically confirmed cases of this type of dissection have been rarely reported.