Pseudomyxoma peritonei (PMP) is a rare disease that is characterized by a large amount of mucinous ascites with peritoneal and omental implants. The etiology of the disease remains unclear. Histologically, two main categories have been described: disseminated peritoneal adenomucinosis (DPAM) and peritoneal mucinous carcinomatosis (PMCA). It is commonly diagnosed incidentally at laparotomy. Most investigators agree that radical surgical debulking and appendectomy are the cornerstone of treatment, but the optimal management of the disease remains controversial. The role of intraoperative and intraperitoneal chemotherapy has been evaluated by a number of authors. The clinical outcomes vary widely between the benign and the malignant forms and between the different treatment modalities. We discuss the pathology, origin, clinical presentation, diagnosis, treatment, and prognosis of PMP.