In this study, 13 ARF and 12 cats with CRF and 10 healthy cats were used as materials. Hematological and serum biochemical examinations as well as EPO analysis were performed after clinical examination. ARF or CRF were diagnosed based on urine analysis supported by increased serum urea (p<0.001) creatinin levels (p<0.05), and reduced PCV (p<0.001), comparing with control values. Also, EPO concentration was lower in CRF than in ARF and control. PCV, RBC and Hb values of CRF were lower than those of ARF (P<0.001). It was concluded that EPO concentration may be decreased due to impaired renal tissue in CRF.