Objective: a case of peritoneal strumosis is presented for making a review of the literature published about these histological tumors and their clinical characteristics. Case presentation: a 48-year-old patient, having a history of left side oophorectomy 34 beforehand due to a benign ovarian tumor, consulted at the Caribe Teaching Hospital (a reference centre for the Bolivar department) as she had pain in the left hypochondrium. Physical exam: abdominal mass confirmed by ultrasound and abdominal computerized tomography. A 15.5 x 10.5 x 7 cm retroperitoneal mass was found during exploratory laparotomy which was removed. Microscope analysis revealed thyroid tissue consisting of follicles having typical structure, constituting a peritoneal strumosis. Materials and methods: a literature review was made of five databases (Medline, Emsco, PubMed, Science Direct and Cochrane Reviews), using search keywords [Title/Summary]: “peritoneal struma”, “peritoneal strumosis” ad “struma ovarii”; 15 bibliographical citations were included. Conclusions: peritoneal strumosis is an infrequently occurring lesion which is associated with mature cystic teratoma of the ovary, whose pre-operation diagnosis is difficult. This is a new case published in the worldwide literature.