Erythropoietin(EPO) is an indispensable erythropoietic hormone, produced mainly from kidneys in adult, and the production declines with progression of chronic kidney disease(CKD). Renal EPO-producing cells(REPs) are peri-tubular interstitial fibroblasts. Dysfunction and myofibroblast transformation of REPs have been reported in rodent models of kidney injuries. Despite the crucial importance of EPO in health and diseases, many aspects of REPs remain to be elucidated because of technical difficulties to investi- gate the cells in vivo. This review will summarize our recent progress in characterization of REPs. We also summarize the role REPs play in kidney fibrosis and their unique character "plasticity". Future therapeutic approach targeting REPs to treat both anemia and fibrosis in CKD will also be discussed.