INTRODUCTION: Patients with inflammatory bowel disease (IBD) present flares during the disease course, which could be triggered by aggressive disease, infection, microbiota changes or medication compliance, among other. Cytomegalovirus (CMV) infection has been found to be more prevalent among IBD patients requiring hospitalization. The aim of this study is to compare the inpatient outcomes for patients admitted with an IBD flare with and without concomitant CMV infection. METHODS: This was a retrospective cohort study using the 2014 National Inpatient Sample, the largest publicly available inpatient database in the United States. Inclusion criteria were age older than 18 years and a primary ICD-9 CM code for any diagnosis of IBD flare. There were no exclusion criteria. The primary outcome was in-hospital mortality. The secondary outcomes were morbidity measured by intensive care unit (ICU) admission, shock, multi-organ dysfunction syndrome (MODS), malnutrition and need for partial/total colectomy, and resource utilization measured by length of hospital stay (LOS), total hospitalization charges, ultrasound (US), CT abdomen and colonoscopy need. Patients with IBD flare were classified as having or not CMV infection diagnosis using ICD-9 CM codes. Odds ratios and means were adjusted for the following confounders using multivariate regression analysis models: age, sex, race, median income in the patient's zip code, hospital region, rural location, size and hospital teaching status. RESULTS: 90,920 patients with IBD flare were included in the study, from which 195 (0.21%) had a diagnosis of CMV infection. Mean age was 42.4 years and 53.5% of patients were female. The population was predominantly Caucasian (73%). The in-hospital mortality was higher among patients without CMV infection (0.28% vs 0%). On multivariate analysis, patients with CMV infection had higher risk of undergoing total/partial colectomy (OR 6.72, P < 0.01) and need for colonoscopy (OR 6.72, P = 0.01), with longer LOS and higher hospital charges (P < 0.01). There were no differences for other markers of morbidity or resource utilization. All adjusted odds ratios, adjusted means and P values are shown in Table 1. CONCLUSION: CMV coinfection in patients admitted to the hospital with IBD flare had higher odds of undergoing colectomy, while presenting higher hospitalization costs and length of stay. However, no impact in mortality was found in this specific group.