BACKGROUND & AIMS: Previous studies of lower intestinal bleeding (LIB) have limited power to study mortality. We sought to identify characteristics associated with in-hospital mortality in a large cohort of patients with LIB. METHODS: We used the 2002 Healthcare Cost and Utilization Project Nationwide Inpatient Sample to study a cross-sectional cohort of 227,022 hospitalized patients with discharge diagnoses indicating LIB. Predictors of mortality were identified by using multiple logistic regression. RESULTS: In 2002, an estimated 8737 patients with LIB (3.9%) died while hospitalized. Independent predictors of in-hospital mortality were age (age >70 vs <50 years; odds ratio [OR], 4.91; 95% confidence interval [CI], 2.45-9.87), intestinal ischemia (OR, 3.47; 95% CI, 2.57-4.68), comorbid illness (>or=2 vs 0 comorbidities, OR, 3.00; 95% CI, 2.25-3.98), bleeding while hospitalized for a separate process (OR, 2.35; 95% CI, 1.81-3.04), coagulation defects (OR, 2.34; 95% CI, 1.50-3.65), hypovolemia (OR, 2.22; 95% CI, 1.69-2.90), transfusion of packed red blood cells (OR, 1.60; 95% CI, 1.23-2.08), and male gender (OR, 1.52; 95% CI, 1.21-1.92). Colorectal polyps (OR, 0.26; 95% CI, 0.15-0.45), and hemorrhoids (OR, 0.42; 95% CI, 0.28-0.64) were associated with a lower risk of mortality, as was diagnostic testing for LIB when added to the multivariate model (OR, 0.37; 95% CI, 0.28-0.48). Hospital characteristics were not significantly related to mortality. Predictors of mortality were similar in an analysis restricted to patients with diverticular bleeding. CONCLUSIONS: The all-cause in-hospital mortality rate in LIB was low (3.9%). Advanced age, intestinal ischemia, and comorbid illness were the strongest predictors of mortality.