Our patient was a 31-year-old man who presented with right flank pain. Computed tomography revealed multiple tumors in the liver and lungs, with marked elevation of serum human chorionic gonadotropin (HCG) and alpha-fetoprotein (AFP) levels. In addition, no testicular abnormalities were detected by palpation or ultrasonography. On the bases of these results, the patient was diagnosed with extragonadal germ cell tumor and was therefore started on chemotherapy with bleomycin, etoposide, and cisplatin (BEP). However, the result of a subsequent blood test showed marked pancytopenia at the initial stage of treatment. We speculated that the cause of anemia was not only bone marrow suppression but also intratumoral hemorrhage, collectively termed choriocarcinoma syndrome. After conservative treatment involving blood transfusion and administration of granulocyte colony-stimulating factor, he recovered. After several chemotherapy sessions, the levels of all tumor markers returned to normal. Finally, the patient underwent hepatectomy for residual tumors ; but, the resected specimen showed no viable cancer cells. Currently, the patient is free from disease since the last chemotherapy session, administered 5 months ago.