Background: Acute lower gastrointestinal bleeding (LGIB) is an alarming indication and common disease with annual admission of 0.15% with mortality rate of 5-10%. LGIB is caused by neoplastic and non-neoplastic lesions. Objective: The aim of the present study was to evaluate frequency of patients admitted to Medical Intensive Care Unit (MICU) of Zagazig University Hospitals (ZUH) with lower gastrointestinal tract bleeding. Patients and methods: A prospective cohort study included 266 subjects and carried out at in Intensive Care Unit, Faculty of Medicine, Zagazig University. All studied population were subjected to full history taking, general examination, laboratory investigation and colonoscopy examination. Results: Age of the studied cases ranged from 18 to 75 years with mean 46.24 years and more than half of them were males (53.3%). The most frequent presentation among the studied cases was hematochezia (95%). Colonoscopic findings among the study population (n=257) showed that 5.8% had diverticular disease, 32.3% had inflammatory alteration and 2.3% had solitary ulcer. Conclusion: AcuteLGITB is a common and challenging problem in MICU of ZUH with ulcerative colitis, bleeding piles, and malignancy as the major underlying causes. Colonoscopy represents the most important diagnostic modality.