Three cases of long-standing ulcerative colitis and invasive adenocarcinoma are described. In all three cases, pre-operative rectal and/or colonoscopic biopsies demonstrated the presence of a villous adenoma: two without dysplasia and the third with moderate dysplasia. The presence of structures compatible with villous adenoma should be, even in the absence of epithelial dysplasia, an indication for panproctocolectomy in patients with long-standing ulcerative colitis.