One hundred and seventeen consecutively detected Chinese patients, 100 males and 17 females, with HLA-B27-Positive acute anterior uveitis (AAU) were studied in the uveitis clinic at the National Yang-Ming Medical College and Veterans General Hospital during a 3-year period from January 1984 to December 1986. The ages of onset of uveitis ranged from 8 to 76 years and averaged 38.2, with most of them (63.8%) distributed between 30 and 59 years and a peak incidence in the thirties. Of the 137 uveitis attacks observed during the follow-up, 60.6% manifested as serous iridocyclitis and 39.4% highly fibrinous. Mutton-fat keratic precipitates were never noted. Of the 117 patients, 78 (66.7%) had recurrent uveitis attacks. The average interval between successive attacks was longer than 1.5 years in 50 (64.1%) of the 78 patients. All patients were unilaterally involved in an AAU attack. Of the 78 patients with recurrent uveitis attacks, 25.6% had an ipsilateral eye suffering from uveitis attacks and 74.4% had uveitis attacks involving either eye. In viewing the distribution of AAU attacks, a significant monthly variation was found (p less than 0.0001) with the highest incidence from December to March. Posterior synechiae and cataract were the most common two persistent ocular complications, which were present in 31.4% and 14.3% of the diseased eyes respectively. The visual prognosis was generally good with 90.3% of the diseased eyes having a visual acuity better than 0.5.2+ Among the 117 patients, 75.2% had an association with seronegative spondylarthropathies, which included ankylosing spondylitis (50.4%), probable ankylosing spondylitis (6.8%), Reiter's disease (12.0%), juvenile rheumatoid arthritis (4.3%) and psoriatic arthropathy (1.7%).(ABSTRACT TRUNCATED AT 250 WORDS)