Colonic lipomas are rare benign lesions, detected accidentally. These are often asymptomatic, but large lipoma may produce symptoms as abdominal pain, nausea, weight loss, diarrhea, constipation, hemorrhage, and intussusception. Colonic lipomas are more often localized in the ascending colon: literature reports less than 20 symptomatic cases situated in the descending colon. We report the case of a young man with a colonic giant lipoma diagnosed at Computed Tomography, who presented with rectum bleeding and 5-kg weight loss. The case was interesting because of the patient's young age, the tumor's location in the left side of the colon and the giant size (5.5 cm).