Immature teratoma of ovary is a rare tumor, representing less than 1% of ovarian neoplasm, and arising from the primordial germ cell layer, and occurring primarily in young adult. Prior to the advent of combination chemotherapy prognosis of these patients was poor. Multiple agent chemotherapy has dramatically improved the prognosis of immature teratoma. Treatment involves surgical resection, usually followed by chemotherapy, result in transformation or evolution into a mature teratoma form of disease. By direct spread metastasis mainly happens with the surroundings internal organs, and the distant metastasis which lead the blood vessel is rare. A thirty three year old female underwent percutaneous needle aspiration for pulmonary metastatic tumor from immature teratoma. These specimens from the lung revealed no malignant findings. The concept of possible chemotherapeutic "retroconversion" or "in situ destruction" of immature tissue may be the mechanism for this result. Retroconversion of ovarian immature teratoma is rare reported was found which dealt with pulmonary metastatic lesion histologically. We report a rare case of mature form pulmonary metastasis of ovarian immature teratoma with a review of relevant literature.