Peritoneal pseudomyxoma is a rare disease, classically detected by the discovery of “gelatin” during a laparotomy. Thanks to immunohistochemistry, it is now accepted that its origin is mainly appendicular and not ovarian. It is a “borderline” malignant pathology due to its inevitable persistence and progression in the absence of appropriate therapeutic management: combination of cytoreduction surgery and intraperitoneal perioperative chemotherapy (intraperitoneal chemohyperthermia and/or immediate postoperative intraperitoneal chemotherapy), within specialized centers. Its main prognostic factors are dominated by the importance of the surgical history, the radicality of the cytoreduction and especially by the histopathological grade. We report a case of peritoneal pseudomyxoma detected at the advanced stage whose origin is a ruptured appendicular mucocele disseminated in the peritoneal cavity.