We present the first case report of the use of sorafenib and S-1 for the treatment of renal cell carcinoma (RCC) producing granulocyte colony-stimulating factor (G-CSF). This entity is clinically rare and has a poor outcome. A 78-year-old Japanese man presented with macrohematuria, left flank pain, and a palpable mass. Laboratory data showed marked leukocytosis with increased serum and urinary G-CSF. The histopathological diagnosis was unclassified RCC. New combination therapy with sorafenib and S-1 exerted a therapeutic effect and apparently decreased serum and urinary G-CSF levels, although the patient died of gastrointestinal perforation. The use of combined sorafenib and S-1 may be worthy of consideration in the treatment of RCC producing G-CSF.