Pseudomyxoma peritonei is a disease characterized by the progressive accumulation of mucinous ascites within the abdomen and pelvis. Metastatic disease outside the peritoneal cavity is unusual. Gastrointestinal function is lost from external compression of stomach, small bowel, and large bowel. We present three cases of pseudomyxoma peritonei which were treated by different therapeutic methods. Case 1 was a 61-year-old man who underwent treatment by appendectomy with administration of Cisplatin and Doxorubicin hydrochloride into the intraperitoneal cavity. Case 2 was a 64-year-old woman who underwent bilateral oophorectomy with administration of Cisplatin and ADM into the intraperitoneal cavity. About 4 years after the first operation, she died of peritonitis due to small and large bowel perforations underlying recurrent tumors. Case 3 was a 79-year-old woman who underwent surgery to evacuate about 4000 ml of mucinous ascites, and received intraperitoneal administration of 5-Fluorouracil (500 mg/day) for 5 days without severe complications.