Two cases of primary extragonadal germ cell tumor of retroperitoneal origin are reported. One was a 26-year-old man complaining of back pain. He had a large retroperitoneal tumor with lung, liver and supraclavicular lymph node metastases. He was referred to us after being treated for malignant lymphoma. The serum AFP, beta-subunit of human chorionic gonadotropin (hCG-beta), CEA and CA-19-9 were elevated. The retroperitoneal disease was treated surgically and with radiotherapy. The pathological diagnosis was that of embryonal carcinoma and teratoma. The lung, liver and supraclavicular lymph node metastases disappeared completely after two courses of cisplatin-based chemotherapy. While further chemotherapy was postponed due to myelosuppression, the disease relapsed and was resistant to subsequent therapy. The patient died twelve months after he first saw us. The second case was that of a 36-year-old man complaining of edematous legs and external genitalia. He had an extensive retroperitoneal tumor with multiple pulmonary metastases. The serum AFP level was high. Suspected of having an extragonadal germ cell tumor, he was referred to us promptly. Cisplatin-based chemotherapy coupled with resection of residual retroperitoneal and pulmonary disease resulted in complete remission. The pathological diagnosis was that of possible embryonal carcinoma. Further chemotherapy was given as scheduled, using granulocyte colony-stimulating factor. The patient has been in complete remission for two years. The chemotherapeutic regimen and surgical policy in the treatment of the two patients were essentially same. Early diagnosis, adequate initial therapy and the use of granulocyte colony-stimulating factor may be relevant to the favorable prognosis in the latter case.