Ulcerative colitis (UC) is an inflammatory disease of the colon. Involvement of the small bowel is limited to backwash ileitis or pouch-related conditions. Here, we report two men with UC who presented with small bowel inflammation and even perforation, within 1 month after subtotal colectomy. Endoscopy showed diffuse enteritis. Histology showed marked apoptosis of epithelial cells in both cases. One patient responded to steroids and the other to a calcineurin inhibitor. Both patients had no evidence of Crohn's disease in the small intestine before this event. Several more cases of small intestinal lesions in patients with well-established UC have been reported. The majority typically presented shortly after colectomy and responded well to steroids. The pathogenesis of this enteritis is unknown, but seems to be distinct from Crohn's disease and may be associated with UC and colectomy.