The development of an invasive adenocarcinoma arising from gastric mucosa within the neo-esophagus of a Collis gastroplasty is uncommon. We report 1 patient in whom an adenocarcinoma developed 18 years postoperatively, and who was treated by total gastrectomy. We suggest accurate preoperative evaluation and staging to distinguish tumors arising in the distal esophagus from those arising in the gastric mucosa of the neo-esophagus, and recommend an approach to management of these tumors.