Primary choriocarcinoma of the lung is extremely rare and have been reported ten and several cases only in the literature. It is very difficult to confirm the "Pure primary pulmonary choriocarcinoma" clinically, so most cases that have been reported in the literature confirmed by autopsy and the prognosis is relatively poor compared with metastases. We experience one case of the primary pulmonary choriocarcinoma. She was 53 year old multiparous woman[4 ulcorner0 ulcorner2 ulcorner0] who complain right chest pain for 4 years. On plain film and computerized tomogram of the thorax at admission, 2.5cmx3.5cmx5 cm sized, well demarcated ovoid mass was founded on the right middle lobe just below the parietal pleura and growing rapidly on plain film to 5cm x 6.5cm x 7cm after 15 days. We confirm the choriocarcinoma in the lung by percutaneous needle aspiration biopsy and strongly suspect primary after various examination for rule out metastases from the ovary or uterus. We perform middle lobe lobectomy because that can not confirm the primary or the metastases because there are not complete histological examination by bilateral ovariectomy and hysterectomy, and under the belief that extragestational or extragonadal primary choriocarcinoma is more resistant to the chemotherapy, and could be reduce the duration of hospitalization and the amount of chemotherapy used to achieve remission On 14th postoperative day, serum p-HCG level was returned to normal limit, and perform chemotherapy two times on 3rd and 5th week for prevention surgical traumatic hematogenous metastases or undetected microfocus, but the patient expire on 68th postoperative day due to intracerebral hemorrhage in the intracranial choriocarcinoma which strongly suspected surgical traumatic hematogenous metastases.etastases.