Purpose: Ulcerative colitis (UC) is associated with an increased risk of colorectal cancer (CRC).1,2 We compared CRC risk in patients with UC treated with adalimumab (ADA) (with or without other UC treatments) vs. conventional therapy. Methods: Patients aged 18-64 years with ≥2 UC diagnoses (International Classification of Diseases, Ninth Revision [ICD-9]: 556) were identified from the Thomson Reuters MarketScan® database between July 1, 2000, and June 30, 2010. Patients with UC were assigned to the ADA group if they initiated ADA or to the conventional therapy group if they initiated a corticosteroid, aminosalicylate, or immunosuppressant without use of ADA, etanercept, or infliximab. Patients had to be free of CRC (ICD-9: 153, 209.10, 209.13-209.16); benign neoplasm of the colon, rectum, or anal canal (ICD-9: 211.3, 211.4); and other malignancies (ICD-9: 140-152, 154-208, 209.0, 209.11, 209.12, 209.17, 209.2-209.6, 273.0, 273.3) and have continuous health care eligibility for 6 months before (baseline) the qualifying prescription fill (index date). Patients were followed from their index date to the end of their eligibility. Time to diagnosis of CRC was compared between patients initiating ADA and conventional therapy using Kaplan-Meier survival curves and Cox proportional-hazard models, adjusting for demographics (age, sex, and year of initiation) and gastrointestinal comorbidities that differed between groups at baseline (noninfective gastroenteritis and colitis as well as gastrointestinal hemorrhage). Results: 23,867 patients with UC were included: 581 who initiated ADA and 23,286 who initiated conventional therapy. Before adjusting for baseline demographic and comorbidity factors, patients treated with ADA and conventional therapy had a similar CRC risk at Years 1 and 2 after initiation of therapy (CRC-free rate at Year 1: 99.78% vs. 99.75%, P=0.812; at Year 2: 99.78% vs. 99.59%, P=0.621). After adjusting for baseline factors, ADA-treated patients were approximately 1.36 times less likely to develop CRC compared with those treated with conventional therapy at Year 2 after initiation of therapy (hazard ratio=0.735, 95% CI: 0.101-5.373, P=0.762); however, this result was not statistically significant. Conclusion: No significant difference in CRC risk was observed in patients with UC treated with ADA and those treated with conventional therapy in both the unadjusted and adjusted analyses.