From 1949 through 1978, 31 patients with renal metastasis were diagnosed in a total of 448 cases of choriocarcinoma admitted to our hospital, giving an incidence of 6.9%. Renal metastasis was invariably preceded by pulmonary metastases and usually accompanied by other visceral metastases, indicating that renal metastasis is the result of dissemination of tumor cells secondarily from lung metastasis through the general circulation and should be categorized as arterial metastasis. Pyelogram is useful in the presence of medullary invasion by the tumor. Renal metastatic tumors are very sensitive to chemotherapy. Good response to chemical agents may be due to high drug concentration attained in the kidney tissue during excretion. Since successful treatment of renal metastasis by chemotherapy alone may be obtained, patients can be spared a major operation without jeopardizing the prognosis.