OBJECTIVES: To estimate the cost- effectiveness of temsirolimus as a treatment option in poor risk renal cell carcinoma compared with interferon-α and from the perspective of national health insurance in Taiwan. METHODS: A decision-analytic model was developed to estimate the cost effectiveness of temsirolimus. Cost and the clinical effectiveness data were obtained from published literature and current reimbursed price published by Bureau of National Health Insurance. All costs and outcomes were discounted at an annual rate of 3%. The effect of parameter uncertainty on cost-effectiveness was explored through extensive one-way and probabilistic sensitivity analyses.  RESULTS: Compared with interferon-a, temsirolimus treatment resulted in an discounted incremental cost per QALY gained of NT$ 4,775,609, based on an estimated mean gain of 0.24 quality- adjusted life years (QALYs) per patient; and a cost per life-year gain of NT$ 2,512,048. Cost-effectiveness estimates were most sensitive to changes in hazard ratios for overall survival between temsirolimus and interferon-a. CONCLUSIONS: In comparison with interferon-a, the ICER (NT$4,775,609) for temsirolimus as a treatment in poor risk renal cell carcinoma, was found to be much higher than the threshold suggested by the World Health Organization. Therefore, temsirolimus could not be regarded as a cost-effective option from the National Health Insurance perspective.