The article describes a case of pseudomyxoma peritonei. The disease is uncommon. The origin is usually a malignant process in the ovary or appendix. The disease spreads to the peritoneal surface, which becomes studded with mucinous bulks. The patient suffered from abdominal discomfort and distension. 80-85% of persons with this disease die within ten years. The disease must be treated with extensive surgery. The case demonstrates the effect of adjuvant chemotherapy. The treatment of pseudomyxoma peritonei must involve co-operation between surgery and oncology.