We present the case of a 53-year-old lady with incidental diagnosis of struma ovarii 10 years after total thyroidectomy due to papillary thyroid carcinoma. The disease was diagnosed owing to high levels of serum thyroglobulin. The patient underwent exploratory laparotomy with total hysterectomy and bilateral salpingo-oophorectomy. Close follow-up was proposed and her prognosis is excellent.