Background Tofacitinib is a Janus kinase inhibitor approved for the treatment of ulcerative colitis (UC).Aim To evaluate effectiveness, safety and use of tofacitinib in daily practice.Methods UC patients initiating tofacitinib were prospectively enrolled in 15 hospitals in the Netherlands. Corticosteroid-free clinical remission (short clinical colitis activity index [SCCAI] <= 2), biochemical remission (faecal calprotectin level <= 250 mu g/g), combined corticosteroid-free clinical and biochemical remission, predictors of remission, safety outcomes, treatment dose and effect on lipids were determined at weeks 12 and 24. Endoscopic outcomes were evaluated in centres with routine endoscopic evaluation.Results In total, 123 UC patients (95% anti-TNF, 62% vedolizumab and 3% ustekinumab experienced) were followed for a median duration of 24 weeks (interquartile range 12-26). The proportion of patients in corticosteroid-free clinical, biochemical, and combined corticosteroid-free clinical and biochemical remission rate at week 24 was 29% (n: 22/77), 25% (n: 14/57), and 19% (n: 11/57) respectively. Endoscopic remission (Mayo = 0) was achieved in 21% of patients at week 12 (n: 7/33). Prior vedolizumab exposure was associated with reduced clinical remission (odds ratio 0.33, 95% confidence interval [CI] 0.11-0.94). At week 24, 33% (n: 14/42) of patients still on tofacitinib treatment used 10 mg twice daily. In total, 33 tofacitinib-related adverse events (89 per 100 patient years) occurred, 7 (6% of total cohort) resulted in discontinuation. Cholesterol, HDL and LDL levels increased during induction treatment by 18% (95% CI 9-26), 18% (95% CI 8-28) and 21% (95% CI 14-39) respectively.Conclusion Tofacitinib is an effective treatment for UC after anti-TNF and vedolizumab failure. However, a relatively high rate of adverse events was observed resulting in discontinuation in 6% of patients.