Retroperitoneal lymphangiomyoma is rare abdominal finding of lymphangiomyomatosis (LAM). We report here on a case of retroperitoneal lymphangiomyoma and this is the first case that? been seen in the Korean literature. Retroperitoneal lymphangiomyoma associated with pulmonary LAM has rarely been reported in radiologic literature. The charateristic findings of this case are a prominent solid component and retroperitoneal lymphadenopathy mimicking a malignant tumor. A 45-year-old woman was admitted for further evaluation of a lower abdominal mass that could be palpated for 2 weeks. US findings showed relatively well-defined mass with septated cystic portions and echogenic solid portions in the lower abdomen. CT findings revealed a well-demarked retroperitoneal mass with septated cystic portions and enhancing solid portions at the right lower abdomen, and there were multiple retroperitoneal lymphadenopathy at the lower abdomen. The patient underwent a mass excision. The pathologic findings were retroperitoneal lymphangiomyoma with multiple lymph node involvement.