Renal cell carcinoma (RCC) with sarcomatoid features has an aggressive course. There is no standard treatment for this histological subtype. Some authors have previously reported the use of chemotherapy, but the activity of new agents against renal carcinoma with sarcomatoid differentiation has to be formally evaluated. Temsirolimus, an inhibitor of the mammalian target or rapamycin, is active in RCC, including those tumors with non-clear histologies. We have tested the activity of this agent in three consecutive patients. A first patient showed a rapid progression, dying 2 months after the diagnosis. The second patient showed clinical improvement and a partial response to lung metastasis that was maintained for 14 months. The third patient is still alive, evaluated as stable disease after 7 months on temsirolimus. Importantly, toxicity was not a main issue during the use of temsirolimus and only grade 2 hyperglycemia, asthenia, hyperlipidemia, and pleural effusion were detected. Temsirolimus is a valid therapy in this subset of patients, with some lasting stabilizations and with manageable toxicity.