Massive lymphorrhea, containing transudative ascites due to a peritonectomy after undergoing surgery for gastrointestinal cancer, accompanied by an extended lymphadenectomy, has occasionally been observed but has usually improved spontaneously within a short period of time. The regeneration of the lymph vessels following lymphadenectomy for gastrointestinal cancer has been postulated. We investigated the regeneration of the lymph vessels in an animal experimental model undergoing a ligation and division of the mesenteric lymph trunk. Lymphangiographical studies were made on the first, fourth, and sixth postoperative day (POD 1, 4, 6). No regeneration of the lymph vessels was observed within 24h after the division. On POD 4, a recommunication due to regeneration was recognized in 60%. By POD 6, the lymphatics of all cases had recommunicated. This phenomenon of lymphatic regeneration was therefore confirmed in the medium-sized lymph vessels.