Interferon-alpha (IFN-α) has been used in systemic treatment for metastatic renal cell carcinoma (mRCC). IFN-α has at least 14 subtypes, each of which has different biological activity. There have been reports that mRCC resistant to an IFN-α treatment responded to another IFN-α subtype. This study was performed to evaluate the effectiveness of alternation of different IFN-α subtypes for mRCC that did not respond to initial IFN-α treatment. In our department and associated institutions, alternating therapy of IFN-α was provided for 15 initial IFN-α refractory mRCC cases from June 2005 to September 2008. Among the 15 patients, the effects of alternating IFN-α therapy were as follows: complete response (CR), 0 cases; partial response (PR), 1 case; stable disease (SD), 3 cases; progressive disease (PD), 11 cases. The response rate (CR+PR) was 7% and disease control rate (CR+PR+SD) was 27%. No severe side effects were observed in any of these cases. The PR case is still in PR 21 months after alternating IFN-α therapy. Among the three SD cases, one has continued SD for 14 months and the other for 12 months. Alternating IFN-α therapy for mRCC can be attempted even if other cytokines are not effective.