Treating organ recipients who have metastatic renal cell carcinoma (mRCC) is challenging because of the dilemma between transplant-required immunosuppression and cancer control via boosting immunity with immunotherapy. We report such a patient whose case was successfully maintained only with temsirolimus and low-dose steroids, while achieving good allograft function and oncological outcomes. After removal of his primary renal cancer, a kidney recipient was found to have multiple metastases. Since recovery from surgery he has been administered 25 mg/wk temsirolimus for 2 more years. His mRCC is in partial remission, the serum creatinine level has been stable (∼ 1.6 mg/dL), and the performance score has been good. Adverse effects encountered include transient transaminitis, dyslipidemia, and poorly controlled hyperglycemia. The pharmacokinetics of sirolimus (the major first metabolite of temsirolimus) is depicted to speculate the underlying mechanism. To our knowledge, this is the first sustainable success using temsirolimus-based immunotherapy (both immunosuppression and cancer therapy) in a transplant recipient who has mRCC.