Peritoneal carcinomatosis (PC) occurs in roughly 1/3 of patients with GI cancers and is mainly seen with tumors of gastroesophageal, pancreatic, colorectal or appendiceal origin. It is usually a relatively late event in the natural history of the disease and implies a poor prognosis in many cases. Series suggest that patients with PC arising from upper GI primaries have a 3-6 month life expectancy and those with colorectal primaries about a 14 month median survival. Patients with well differentiated mucinous appendix cancers (informally known as jelly belly) often have a much better prognosis. Those patients without bowel obstruction can be managed with chemotherapy with acceptable results but treatment is entirely palliative. Surgical intervention is often required. Many centers offer surgery to maximally debulk peritoneal disease followed by Hyperthermic Intraperitoneal Chemotherapy or HIPEC. Proponents of this approach suggest that it is potentially a curative therapy. Only two small randomized trials exist and their interpretation is hampered not only by their size but by the heterogeneity of the patients included. The largest study includes both patients with indolent appendiceal cancers and those with poorly differentiated colorectal cancers. It seems clear that the former do benefit by maximal debulking. It is not clear whether HIPEC adds incrementally to physical debulking as no trials have evaluated them separately. Attempts at large scale trials include a US intergroup study that accrued few patients and was closed without enough patients to make even preliminary conclusions. At Ohio State University we perform cytoreductive surgery aimed at maximal debulking routinely in patients with mucinous appendix cancers and are selective in using the approach in patients with colorectal cancer limited to the peritoneal cavity after response to chemotherapy is seen and in individuals with relatively slow growing disease. When performed this procedure should be done in centers of excellence.