In lower gastrointestinal bleeding (LGIB), it is very important to stratify the risk of LGIB for a proper management. OBJECTIVE: Identity the independent risk factors to mortality and severity (require critical care, prolonged hospitalization, reebleding, re hospitalization, politrasfusion, surgery for bleeding control) in LGIB. MATERIALS AND METHODS: It is an analytic prospective cohort study, performed between June 2016 and April 2018 in a tertiary care hospital. Independent factors were determined using binomial logistic regression. RESULTS: A total of 98 patients were included, of which 13 patients (13,3%) died, and 56 (57,1%) met severity criteria. The independent risk factor for mortality was Glasgow scale under 15, and for severe bleeding were: Systolic blood pressure under 100 mm Hg, albumin lower than 2,8 g/dL. CONCLUSIONS: The frequency of mortality and severe LGIB is high in our population, the principal risk factors were systolic blood pressure under than 100 mm Hg, Glasgow score lower than 15, albumin lower than 2,8 g/dL. Identifying these associated factors would improve the management of LGB in the emergency room.