Background : More than 90% of dialysis patients respond in a dose-dependent manner to erythropoietin(EPO) administration and the others are resistant. The causes of EPO resistance are iron deficiency, vitamin deficiency, severe hyperparathyroidism, aluminum toxicity, and inflammation. Much literature has been published concerning iron deficiency and its role in EPO resistance. However little attention has been given to the contribution of inflammation to the EPO-resistant anemia observed in hemodialysis patients. Methods : In the present study, we examined the contribution of parathyroid hormone levels, iron idices, normalized protein catabolic rate(nPCR), Kt/Vurea, albumin, and C-reactive protein(CRP) to erythropoietin resistance index(weekly rhEPO dose/body weight/hematocrit; ERI) in clinically stable 48 hemodialysis patients. Results : The factors correlated with ERI were CRP(R=0.608, p<0.01), ferritin(R=0.460, p<0.01) and serum albumin(R=-0.359, p<0.05). In stepwise multiple regression analysis, the independent factor affecting on ERI was CRP(β=0.620, p<0.01). Comparing high CRP group(≥0.4 mg/dL) with normal CRP group(<0.4 mg/dL), there were significant differences in serum albumin, creatinine, ferritin, and ERI. Conclusion : Acute-phase response, assessed by the level of CRP, was the most important predictor or EPO resistance in stable hemodialysis patients.(Korean J Med 58:510-515, 2000)