Wegener granulomatosis (WG) is an idiopathic small vessel vasculitis involving primarily airway and kidneys. Intestinal involvement of WG is rare and usually occurs after several years of WG and its treatment. We report a case of WG, presented initially as rapid-onset hemorrhagic pancolitis without any preexisting or concurrent illness or any medication use. A 79-year-old previously healthy woman presented with 2-day duration of bloody diarrhea. Colonoscopy showed pancolitis with numerous ulcers; the biopsy showed foci of inflammation, ulceration and hemorrhage in the lamina propria, without features of chronic inflammatory bowel disease. Her stool studies were negative for infection. She subsequently developed pulmonary hemorrhage and kidney dysfunction. Kidney biopsy showed pauci-immune necrotizing glomerulonephritis. She responded to a combination therapy of steroids, cyclophosphamide and plasmapheresis with resolution of intestinal and pulmonary symptoms and improvement of kidney function. This case represents the first known example of colitis as an initial presentation of WG without confounding etiologic factors. Hemorrhagic colitis, although uncommon, may be the major presenting feature of WG.