We examined various prognostic factors of metastatic renal cell carcinoma. Patients who had metastasis at nephrectomy (A group, 38 cases) and those who had metastasis as recurrent tumors after nephrectomy (B group, 38 cases) entered in this study. Five-year survival rate of total cases after confirmation of metastatic foci was 15% and there was no statistical significant difference between A and B groups. Several pathological factors were related to poorer prognosis and included large diameters of original tumors, positive lymph nodes, higher grade tumors and non-clear cell type tumors. Patients who have a solitary lung metastasis showed better prognosis compared to those with multiple lung metastases or metastases of other organs. Two factors related to treatment were shown to contribute to better prognosis. These were the response to interferon alfa (IFN alpha) and the possibility of total resection of visible metastatic tumors. Patients who belong to A group were shown to achieve markedly better therapeutic benefit from IFN alpha or IFN alpha plus anticancer drugs. Five-year survival rate for the responders was 40%, as compared to less than 5% for the non-responders. Ten-year survival rate for patients with metastasis who had undergone complete resection of visible tumor was 50%, and the for patients belonging to B group Showed 80%. We concluded that these prognostic factors should be considered to decide how to select patients with metastatic renal cell cancer.