Benign metastasizing leiomyoma (BML) is a rare disease, which usually occurs in women with a history of a prior hysterectomy or myomectomy for benign uterine leiomyoma, and has the potential to metastasize to distant sites, such as the lung, lymph nodes, muscular tissue, heart, or retroperitoneum. These lesions are slow-growing, asymptomatic, and usually found incidentally. The prognosis of BML is also excellent. However, there has been debate on the origin and the correct classification of BML, and there are no guidelines for the treatment of BML. We report here on a rare case of BML in both the retroperitoneal cavity and lung in a 48-year-old woman with a history of hysterectomy due to histologically benign uterine leiomyoma. The patient underwent retroperitoneal mass excision and bilateral salpingo-oophorectomy, and then wedge biopsy of two pulmonary nodules was performed additionally 9 days later. Until now, there has been no sign of recurrence and the patient remains asymptomatic. To our knowledge, pulmonary BML is rare and the co-existence of the retroperitoneal metastases after previous hysterectomy is even rarer.