Acute anterior uveitis (AAU) is the most frequently extra-articular manifestation of ankylosing spondylitis (AS). To investigate whether AAU has an association with disease activity, functional ability and physical mobility in AS patients, 146 Chinese AS patients in Taiwan were enrolled in a cross-sectional study. These patients fulfilled the 1984 modified New York criteria and visited the Outpatient Department of the Veterans General Hospital-Taipei from April 2004 to July 2005. Patients completed questionnaires assessing disease activity [Bath Ankylosing Spondylitis Disease Activity Index (BASDAI)], functional ability [Bath Ankylosing Spondylitis Functional Index (BASFI)] and patient's global assessment [Bath Ankylosing Spondylitis Patient Global Score (BAS-G)]. Meanwhile, physical examinations were performed, including Schober test, finger-to-floor, lateral spinal flexion, occiput-to-wall and chest expansion. The history of AAU was accepted only if diagnosed by an ophthalmologist. The prevalence of AAU in this Chinese AS cohort was 15.8% (23/146). Patients with AAU had a significantly higher BASDAI than those without [absolute differences=0.96, 95% confidence intervals (CI): 0.35-1.88]. Additionally, patients with AAU had significantly increased BASFI than those without (absolute differences=1.46, 95% CI: 0.33-2.59). Moreover, there was advanced limitation of physical motility in patients with AAU, including finger-to-floor, occiput-to-wall distances and Schober test, (95% CI: 3.89-16.95 and p=0.046, respectively). Disease duration mildly correlated with BASFI (r=0.24, p=0.003) but not with BASDAI (p=0.838). There was no difference of disease duration between patients with and without AAU (p=0.343). These results suggested that the presence of AAU in AS patients may be associated with higher disease activity, poor functional ability and advanced physical impairment.