Background: Vedolizumab (VDZ) is effective for treatment of ulcerative colitis (UC) and Crohn's disease (CD). In GEMINI trials, anti-tumor necrosis factor (anti-TNF)-naïve patients had a superior response compared with anti-TNF-exposed patients. In real-world experience (RWE), the number of included anti-TNF-naïve patients was low. We aimed to evaluate the effectiveness and safety of VDZ in anti-TNF-naïve patients in an RWE setting.Methods: This retrospective multicenter European pooled cohort study included consecutive active anti-TNF-naïve IBD patients treated with VDZ. The primary end point was clinical response at week 14. Patients with follow-up beyond week 14 and those discontinuing VDZ at any time were included for maintenance outcomes analysis.Results: Since January 2015, 184 anti-TNF-naïve patients from 23 centers initiated VDZ treatment (Crohn's disease [CD], 50; ulcerative colitis [UC], 134). In CD, 42/50 (82%) patients responded by week 14 and 32 (64%) were in clinical remission; 26/50 (52%) achieved corticosteroid-free remission (CSFR). At last follow-up (44 weeks; interquartile range [IQR], 30-52 weeks), 27/35 (77.1%) patients with available data responded to treatment; 24/35 (68.6%) were in clinical remission, 21/35 (60%) were in CSFR. For UC, 116/134 (79.1%) responded to treatment by week 14, including 53 (39.5%) in clinical remission; 49/134 (36.6%) achieved CSFR. At last follow-up (42.5 weeks; IQR, 30-52 weeks), 79/103 (76.7%) patients responded to treatment, 69/103 (67.0%) were in remission, and 61/103 (59.2%) were in CSFR. Adverse effects were reported in 20 (11%) of the patients, leading to treatment discontinuation in 6 (3.3%).Conclusions: VDZ is similarly effective in ant-TNF-naïve CD and UC patients. The efficacy is higher than reported in anti-TNF-experienced patients and is comparable to that of anti-TNF biologics in this population.