Pseudomyxoma peritonei is a rare condition resulting from a ruptured mucin-producing lesion of the appendix or ovary. A search of the records of the New York Hospital revealed 45 appendiceal mucoceles of which four had ruptured, causing pseudomyxoma peritonei. Treatment should consist of evacuation of the mucinous ascites and removal of the mucocele. Repeated operations for correction of intestinal obstruction may be needed, and with aggressive surgical approach, long-term relief or cure may be effected. The role of chemotherapy is uncertain, and external radiation is probably of no value.