The clinical and radiological features, and outcome of 30 patients including 22 females, with the aneurysmal form of aortoarteritis were analysed. The average age at diagnosis was 27.4 +/- 7.2 years. Features which indicated the diagnosis of aneurysmal aortoarteritis included young age, female sex, characteristic location, associated stenotic lesions and the presence of multiple aneurysms. There were 41 fusiform and 18 saccular aneurysms, mostly located in the descending aorta. Diffuse dilatation (n = 24) was seen mainly in the ascending aorta. Two patients had dissecting aneurysms, while one patient had an aneurysm of the left main coronary artery. Both these lesions are rare in aortoarteritis. The aneurysmal form was associated with a higher incidence of aortic incompetence (P less than 0.01) and elevated ESR (P less than 0.001) as compared to the more common non-aneurysmal form. The average follow-up period was 59.7 (+/- 48.1) months. The event-free survival rate was 82.9% at 5 years, similar to that seen in the non-aneurysmal form. These data should be useful to the clinician in the diagnosis and management of the aneurysmal form of aortoarteritis.