Inflammatory eye disease is well recognized in ankylosing spondylitis (AS) but the relationship between the uveitis and the spondyloarthropathy is poorly defined. The following conclusions may be drawn from a study of 1331 consecutive patients with AS: the prevalence of uveitis was 40% (535 subjects), almost half of whom had greater than 5 attacks. Family studies of sib pairs, concordant for AS, showed that uveitis occurred randomly with a concordance for uveitis/no uveitis of only 43%. A comparison of patients with (n = 535) and without (n = 796) uveitis showed no important differences. Analysis of potential trigger factors among 72 patients with recurrent disease revealed no seasonal, infective or other correlation. The removal of an intrauterine device from a woman with severe intractable bilateral uveitis was associated with remission of the eye disease. In summary, although genetic background determines susceptibility to uveitis the pattern of the disease suggests the possibility of random environmental triggers unrelated to the course of the underlying rheumatological disorder.