The aims of the present study were to: (i) develop a clinically useful prognostic classification in Asian patients with metastatic renal cell carcinoma (RCC) by combining metastatic features with several pretreatment parameters; and (ii) evaluate the validity of this prognostic classification. Baseline characteristics and outcomes were collected for 361 patients who underwent interferon-α-based therapy between 1995 and 2005. Relationships between overall survival (OS) and potential prognostic factors were assessed using Cox's proportional hazard model. The predictive performance of the model was evaluated using bootstrap resampling procedures and by using an independent dataset obtained from randomly selected institutions. The predictive accuracy was measured using the concordance index (c-index). Four factors were identified as independent prognostic factors: time from initial diagnosis to treatment, anemia, elevated lactate dehydrogenase (LDH), and poor prognostic metastatic group (liver only, bone only, or multiple organ metastases). Each patient was assigned to one of three risk groups: favorable risk (none or one factor; n = 120), in which median OS was 51 months; intermediate risk (two factors; n = 101), in which median OS was 21 months; and poor risk (three or four factors; n = 102), in which median OS was 10 months. The c-index was 0.72 in the original dataset and 0.72 in 500 random bootstrap samples. In the independent dataset for external validation, the c-index was 0.73. Thus, the new prognostic classification is easily applicable for Asian patients with previously untreated metastatic RCC and should be incorporated into patient care, as well as clinical trials performed in Asia.