Objective: To evaluate the efficacy of anti-tumour necrosis factor (TNF) treatments (given for rheumatological manifestations) in reducing uveitis flares in patients with spondylarthropathy in daily practice. Methods: A retrospective observational study of all patients with spondylarthropathy with at least one uveitis flare treated with anti-TNF in one centre (December 1997-December 2004. The number of uveitis flares per 100 patient-years was compared before and during anti-TNF treatment; each patient was his or her own control. The relative risk (RR) and the number needed to treat (NNT) were calculated. Results: 46 patients with spondylarthropathy treated with anti-TNF drugs had at least one uveitis flare (33 treated with anti-TNF antibodies, infliximab or adalimumab, and 13 with soluble TNF receptor, etanercept). The mean age at first symptoms was 26 years, 71% were men. Patients were followed for 15.2 years (mean) before anti-TNF versus 1.2 years during anti-TNF treatment. The number of uveitis flares per 100 patient-years before and during anti-TNF were, respectively: for all anti-TNF treatments,-51.8 v 21.4 (p = 0.03), RR = 2.4, NNT = 3 (95% confidence interval (CI) 2 to 5); for soluble TNF receptor-54.6 v 58.5 (p = 0.92), RR = 0.9; and for anti-TNF antibodies-50.6 v 6.8 (p = 0.001), RR = 7.4, NNT = 2 (95% CI 2 to 5). Conclusion: Anti-TNF treatments were efficacious in decreasing the number of uveitis flares in patients with spondylarthropathy. Anti-TNF antibodies decreased the rate of uveitis flares, whereas soluble TNF receptor did not seem to decrease this rate. These results could have consequences for the choice of anti-TNF treatment in certain patients.