A patient with Proteus syndrome presented with lower gastrointestinal bleeding due to multiple colonic hemangiomas, a finding which has not been described previously in this syndrome. The patient was a 20-year-old man with features fulfilling the diagnostic criteria for Proteus syndrome. He fulfilled both general criteria (mosaic distribution of the lesions, progressive course and sporadic occurrence) and specific criteria (including epidermal nevus, disproportionate overgrowth of limbs and vascular malformations). Fiberoptic colonoscopy revealed multiple hemangiomas, 0.5-1 cm in diameter, on the left side of the colon. Some gastrointestinal complications have been reported in patients with Proteus syndrome, including rectal polyps, colonic lipomatosis, atrophy of the intestinal villi and intestinal affection with fatty wall thickening but, as far as we are aware, colonic hemangiomas have not previously been reported in this syndrome.