OBJECTIVE Most studies on variant forms of aortic dissection--penetrating ulcer and intramural hematoma--have focused on the initial presenting episode, with scant follow-up. This investigation provides midterm follow-up of penetrating ulcer and intramural hematoma to determine whether the aorta shows healing according to radiography, goes on to dilate, or tends to rupture during later follow-up. METHODS Forty-five patients with penetrating ulcers (n = 26) or intramural hematomas (n = 19) were treated at our institution. Ten patients with penetrating ulcers were male and 16 were female, and their ages ranged from 54 to 87 years (mean 72 years). Eight patients with intramural hematomas were male and 11 were female, and their ages ranged from 54 to 88 years (mean 74 years). These patients all had symptoms of aortic disease. Patients with incidental imaging findings were not considered. RESULTS In the group with penetrating ulcers, rupture occurred during the initial admission in 10 (38%) cases, 17 patients (65%) underwent surgery, and 22 patients (85%) survived to hospital discharge. Among those with intramural hematomas, rupture occurred during the initial admission in 5 cases (26%), 7 patients (37%) underwent surgery, and 16 patients (84%) survived to hospital discharge. Follow-up ranged from 1 month to 12.5 years (mean 3.4 years). No ischemic vascular complications occurred. Imaging follow-up was available for 26 of the 45 patients. Of these, 19% of lesions showed resolution, 23% had worsened, 39% had progressed to typical dissection, and 19% were unchanged. Six late deaths were known to be caused by rupture. In the group with penetrating ulcers, aortic diameter increased from 4.8 to 5.1 cm during the course of 14 months. In the group with intramural hematomas, aortic diameter increased from 5.3 to 5.9 cm during the course of 21 months. Overall survivals were 80% at 1 year, 73% at 3 years, and 66% at 5 years. CONCLUSIONS Intramural hematoma and penetrating ulcer are lesions associated with advanced age. Women predominate. Penetrating ulcer and intramural hematoma rupture both early and late. Radiographically documented worsening, improvement, or frank dissection may occur with time. Aortic growth does occur (0.2 cm per year for penetrating ulcer and 0.4 cm per year for intramural hematoma). Vascular ischemic complications do not occur. Because of the high early rupture rate, the frequency of radiographic worsening, and the documented occurrence of late rupture, we now recommend surgical replacement of the aorta for these virulent vascular lesions as long as the patient's comorbidities do not preclude surgical intervention.