This report demonstrates the cases of a 47-year-old housewife, a 54-year-old female, and an 80-year-old woman in whom pseudomyxoma peritonei was found accidentally during surgery. Pseudomyxoma peritonei is a rare disease. No effective treatment is known. Modern treatments include radical surgical excision with appendicectomy and oophorectomy in women and adjuvant hyperthermic intraperitoneal and systemic chemotherapy. Major causes of morbidity and mortality are bowel obstruction and biliary obstruction. Five-year survival rate, depending on whether the disease is benign or malignant, is about 53-75%. Median survival is about 2 years under surgical management.