Case 1: a 57-year-old woman, who suddenly developed disturbance of consciousness, left spatial neglect, and left hemiparesis, was admitted to our hospital on the day 1. Brain CT scan on the day 2 revealed broad edematous infarction in her middle cerebral artery territory. The dissection of the thoracic aorta was observed with transesophageal echocardiography and brain embolism due to mural thrombus of the dissecting thoracic aorta was suspected. Case 2: a 67-year-old woman, who developed disturbance of consciousness, left spatial neglect, and left hemiparesis, was admitted to our hospital on the day 15. Brain CT scan on the day 15 showed non-edematous infarction in her middle cerebral artery territory. Contrast thoracic CT scan on the day 31 revealed the dissection of the thoracic aorta. No clinical exacerbation was observed, but brain CT scan on the day 94 showed broad infarction in her middle and anterior cerebral artery territories. It is considered that pseudolumen of the dissected thoracic aorta caused occlusion of her right internal carotid artery. Transesophageal echocardiography, or contrast thoracic CT scan should be considered for detection of the dissection of the thoracic aorta in the cases of cryptogenic stroke.