Colonic varices, usually detected by means of colonoscopy, are extremely rare and typically indicative of portal hypertension or chronic hepatopathology. Even more rare are those cases with no underlying disease, or idiopathic colonic varices. The authors report a case of these unexplained varices found during colonoscopy of a 30-year-old man with a 10-year history of diarrhea and occasional bloody stool. A thorough workup was performed, revealing no underlying abnormalities for his varices. Additionally, the authors review the literature of this rare diagnosis. Physicians must rule out hepatic, vascular, and cardiac causes before classifying a case of varices as idiopathic.