Clinical manifestations and immunogenetic aspects of Behçet's disease were investigated in the Veterans General Hospital of the National Yang-Ming Medical College, Taiwan. Diagnosis of Behçet's disease was made according to the diagnostic criteria proposed by the Japanese Research Committee of Behçet's disease. Fifty-three patients including 33 men and 20 women have been diagnosed as having Behçet's disease in the past 10 years; 20 cases with the complete type and 33 cases with the incomplete type. About half of these cases were diagnosed in the past 2 years, predominantly by ophthalmologists. Of the 53 cases, ocular lesions were found in 35 cases, 25 men and 10 women. The ages of the onset of the ocular lesions ranged from 10 to 50 years, with the peak distribution between 20-30 years. Bilateral involvement was seen in 24 men and 8 women, and a total of 67 eyes were affected; 37 eyes (55.2%) had the final visual acuity of 0.1 or lower. Immunogenetic study revealed that the incidence of HLA-B51 was significantly higher in the patients than in the normal population.