BACKGROUND: Few data exist regarding the effectiveness of ustekinumab in inflammatory bowel disease (IBD) patients treated for concomitant psoriasis or psoriatic arthritis.AIMS: to describe the outcomes of IBD patients who received subcutaneous ustekinumab through a dermatological or rheumatological prescription.METHODS: This multicenter, retrospective study included all IBD patients who were started on ustekinumab for concomitant active psoriasis/ psoriatic arthritis, irrespective of IBD activity. The primary endpoint was overall ustekinumab persistence, defined as the maintenance of therapy because of sustained clinical benefit for IBD.RESULTS: Seventy patients (64 Crohn's disease / 6 ulcerative colitis) were enrolled. The median follow-up on ustekinumab therapy was 10.7 months (range, 1.4-67.3). Twelve patients (17.1%) withdrew the treatment after a median of 7.4 months (range, 0.9-23.8). The cumulative probability of maintaining ustekinumab treatment was 97.1% at 6 months and 77.1% at 12 months. Among the 56 patients with baseline active IBD, 34 (60.7%) were in clinical remission at the last follow-up visit. Their cumulative probability of achieving clinical remission was 84.7% and 63.9% at 6 and 12 months, respectively. Two patients stopped ustekinumab for an adverse event.CONCLUSIONS: Subcutaneous ustekinumab had a good effectiveness profile for IBD patients treated for concomitant dermatological or rheumatological conditions.