Pseudomyxoma peritonei is a rare disease, usually diagnosed after the discover of "jelly belly" by laparotomy. With the progress of immunohistochemistry, most authors now acknowledge the appendix to be the principal origin of this disease. Pseudomyxoma peritonei need to considered as border line malignant disease because of its inevitable persistence and progression without adapted therapeutic approach: cytoreductive surgery combined with perioperative intraperitoneal chemotherapy (intraperitoneal chemohyperthermia and/or immediate postoperative intraperitoneal chemotherapy) into specialized centres. The principal prognostic factors are the prior surgical history, the completeness of cytoreduction and especially the histopathologic grade.