Purpose: To review the treatment of primary retroperitoneal mucinous cystadenocarcinoma (PRMC). Case report: A 30-year-old woman had a large retroperitoneal mucinous adenocarcinoma treated with conservative laparoscopic surgery. Two years later, she was found to have bilateral ovarian cysts at the time of cesarean section. Since cystectomies revealed mucinous adenocarcinoma, she underwent complete surgical staging and adjuvant chemotherapy at this time. Conclusion: A rare case of similar cancer in the ovary following treatment for PRMC was described. It is unclear whether the prognosis is improved by oophorectomy. Further cases and long-term follow-up are necessary.