Purpose: Improvement in quality of life (QoL) is an important treatment goal for patients with ulcerative colitis (UC). We evaluated QoL in patients with UC who were treated with azathioprine (AZA), infliximab (IFX), or a combination of the two therapies. Methods: UC SUCCESS was a 16-week, double-blind controlled trial of patients with moderate-tosevere UC (baseline total Mayo score 6-12). All patients had failed corticosteroids, were biologic-naïve, and were AZA/6-mercaptopurine-naïve or had stopped AZA ≥3 months prior. Patients were randomized to treatment for 16 weeks: AZA 2.5 mg/kg + placebo; IFX 5 mg/kg + placebo; or IFX 5 mg/kg + AZA 2.5 mg/kg. Week 8 non-responders in the AZA group were eligible for IFX rescue added to AZA. QoL was assessed with the Inflammatory Bowel Disease Questionnaire (IBDQ) and 36-item Short Form Health Survey (SF-36). Treatment group differences were analyzed with Mann-Whitney U tests. Results: Two hundred thirty nine patients were enrolled. Of 231 patients eligible for efficacy analyses, 75-80% completed the QoL assessments. Improvements in all IBDQ scores were greater in the combination group than either monotherapy group (P<.05, all comparisons; Table). SF-36 physical and mental summary scores (Table) and all eight component scores showed the same pattern of greater improvement in the combination group than either monotherapy group, although not all of these comparisons were statistically significant. Overall, adverse events were similar across treatment arms.Table 1: Mean change in IBDQ and SF-36 scores from baseline to week 16Conclusion: Combination treatment with IFX+AZA resulted in greater improvement in QoL than monotherapy with either IFX or AZA. These data are consistent with previous UC SUCCESS reports, indicating that clinical responses (steroid-free remission, mucosal healing, and Mayo scores) were better with combination IFX+AZA treatment. Disclosure - R Panaccione - Consultancy, advisory board, speaker's bureau fees, or honorarium and travel support to meetings related to this study from the study sponsor, Merck Sharp & Dohme Corp. Consultancy fees and/or speaker fees from Johnson and Johnson and Janssen; S Ghosh - Grants and consultancy fees from Abbott and Janssen. Speaker fees from Abbott, Janssen, and Ferring. S Middleton: Advisory board member for the study sponsor, Merck Sharp & Dohme Corp., and has received honoraria; J Márquez - Speaker's fees from Abbott and Janssen; L Flint - Employee of Merck Sharp & Dohme Corp. at the time the study was conducted and may hold stock options in the company; H van Hoogstraten - Employee of Merck Sharp & Dohme Corp. at the time the study was conducted and may hold stock options in the company. Current employee of a commercial entity relevant to, or that could potentially benefit from, the publication/Disclosure of the subject matter or materials discussed in the manuscript; A Chen - Employee of Merck Sharp & Dohme Corp. and may hold stock options in the company; H Zheng - Employee of Merck Sharp & Dohme Corp. and may hold stock options in the company; S Danese - Consulting, advisory, and speaker's bureau fees and/or honoraria from the study sponsor, Merck Sharp & Dohme Corp. Received consulting fees or lecture fees from Ferring, Takeda, Abbott, Vifor Pharma, Novo Nordisk, Astra Zeneca, UCB, and Pfizer; P Rutgeerts - Consulting fees from Millennium/Takeda, Genentech/Hoffmann-La Roche, Neovacs, Merck Serono, Bristol Myers Squibb, Robats, Tillotts, Pfizer, and Falk Pharma; lecture fees and research support from Johnson & Johnson and Abbott; consulting fees and research support from UCB; grant funding and consulting and advisory board fee or honoraria and travel support to meetings relevant to this study from the study sponsor, Merck Sharp & Dohme Corp. This research was supported by an industry grant from Financial support for this study was provided by Merck Sharp & Dohme Corp., a subsidiary of Merck & Co., Inc., Whitehouse Station, NJ, USA.