A total of 103 cases with ocular involvement of Behcet's disease, seen over a period of 19 years (1970 to 1988), were collected from the ophthalmological departments of 6 major medical centers in Taiwan. The yearly number of patients who first visited these hospitals from 1979 through 1983 was about 5 cases and about 14 cases from 1984 to 1988. The domiciles of the patients were most commonly (51.5%) in Northern Taiwan. All 103 patients were Chinese, of which 78 (75.7%) were men and 25 (24.3%) were women; the male to female ratio was 3.1. Extraocular symptoms of Behçet's disease, major or minor, and their frequencies among these patients included; oral ulcers, 97.1%, skin lesions, 74.8%; genital ulcers, 61.2%; arthritis, 47.6%; gastrointestinal lesions, 14.6%; epididymitis, 5.8%; central nervous system lesions, 2.9%; vascular lesions, 1.9%; pulmonary lesions, 2.9% and urinary lesions, 4.9%. Fifty-one (49.5%) patients were of the complete type and 52 (50.5%) of the incomplete type. The peak distribution of ages at the onset of the ocular lesions, was from 20 to 40 years. As for visual prognosis, 37.9% of the 198 diseases eyes had a visual acuity of 0.5 or better, 9.1% between 0.5 and 0.1, 25.3% between 0.1 and 0.01 and 27.8% were 0.01 or worse. In 24 (12.1%) eyes, the vision was completely lost. In HLA studies, a significantly increased incidence of HLA-A26 (p less than 0.01) and HLA-B51 (p less than 0.001) was found.(ABSTRACT TRUNCATED AT 250 WORDS)