Clear cell renal cell carcinoma (CCRCC) is the most common renal carcinoma and it is often associated with von Hippel-Lindau disease (VHL) gene mutations. CCRCCs with VHL mutations demonstrate hypoxia-inducible factor (HIF) overexpression as well as increased expression of vascular endothelial growth factor (VEGF). Recently, the erythropoietin (Epo) has been found to be upregulated in renal and other tumors associated with VHL disease. Furthermore, Epo and Epo receptor (EpoR) coexpression has also been reported in these tumors. The results provided strong evidence that an autocrine loop is involved in tumorigenesis in VHL disease. We investigated whether Epo and EpoR coexpression also occurs in sporadic CCRCC. Fifty-four sporadic CCRCCs were analyzed. VHL gene mutations were detected in 30 out of 54 tumors. Coexpression of Epo and EpoR was detected in 50 out of 54 tumors regardless of their VHL mutation status. The results suggest that coexpression of Epo and EpoR plays an important role in tumorigenesis of sporadic CCRCC.