Disease severity, immunosuppression, and malnutrition may impact morbidity and mortality of the critically ill patient with inflammatory bowel disease (IBD). The aim of this study was to identify potential predictive factors for mortality among IBD patients requiring admission to an intensive care unit (ICU). All patients with an admitting diagnosis of ulcerative colitis or Crohn's disease presenting to the ICU at the Mount Sinai Medical Center from 2003 to 2008 were retrospectively analyzed. Data regarding IBD-specific features, medications, and surgical outcomes were collected as well as ICU-related morbidity and 30-day mortality. Ninety-five patients were admitted to the ICU out of a total of 6663 IBD-related hospital admissions with an overall 30-day mortality rate of 18.9%. The annual number of ICU admissions of all hospitalized IBD patients increased from 0.1% in 2003 to 2.6% of admissions in 2008. ICU-related variables associated with increased mortality included mechanical ventilation (P=0.0002), vasopressor requirement (P=0.0002), severe sepsis (P=0.0005), acute kidney injury (P=0.001), Acute Physiology and Chronic Health Evaluation II scores (P ≤ 0.0001), hypoalbuminemia (P=0.036), and thromboembolism (P=0.046). On multivariate analysis, elevated Acute Physiology and Chronic Health Evaluation II scores were the only independent predictor of mortality. Although the overall number of ICU admissions among IBD patients was low, the annual incidence rates of admissions are increasing. This patient subgroup had significant in-hospital morbidity and 30-day mortality. Earlier identification of potential risk factors leading to poorer outcome, particularly within the first 24 hours of ICU admission, may impact the triage and subsequent management of these critically ill patients.