A 43-year-old woman underwent a laparotomy with a preoperative diagnosis of acute appendicitis. Based on intraoperative and histopathological findings, the definite diagnosis of peritoneal pseudomyxoma due to a mucinous cystadenocarcinoma arising in the appendix was made postoperatively. When the surgical wound was sutured, a large quantity of gelatinous material was left. For the purpose of cleaning the remnant material, we directed the patient to perform intraperinoneal lavage at home every day, by using a continuous ambulatory peritoneal dialysis (CAPD) system. During the same period intraperitoneal chemotherapy with 5-FU was also given to the patient. With these postoperative adjuvand therapies, the patient is doing well without any signs of recurrence, as of 2 years and 3 months after the operation.