Behçet's disease (BD) is a systemic disease of unknown etiology, characterized by multiple organ involvement. Although its incidence is high in the Mediterranean countries and in Japan, BD is not often found in German patients. We therefore compared the epidemiological and clinical involvement of BD in 39 patients of German and of Mediterranean origin. The first manifestation was oral aphthosis in 72% of patients, followed by eye involvement (62%), skin lesions (25%), and arthritic problems (23%). Eventually, all our patients developed oral aphthosis. Whereas Germans had eye involvement in only 55% of cases (Mediterraneans, 71%), they came up with venous thrombosis or thrombophlebitis more often (64%) as compared with Mediterraneans (29%). The first ocular symptom was anterior uveitis in 87.5% of patients; the visual prognosis was poor due to occlusive retinopathy. Among 22 eyes of 12 patients, 16 had a visual acuity of 0.1 or less after 5 years of disease. We found a similar association with human leukocyte antigen B5 (HLA-B5) in the German patients (66.7%) and in the Mediterranean group (54.4%). There was no significantly higher HLA-B5 association with the uveitis or arthritis type. These results demonstrate a few differences between the two ethnic groups but illustrate that in Germans the disease also has a poor prognosis.