Objective The aim of the investigation is to examine oxidative stress of uremic patients and evaluate the role of renal anemia as a secondary cause of oxidative stress. Methods Lipid peroxidation (LPO) and superoxide dimutase(SOD) are measured in two groups of patients undergoing HD:group I comprises 12 patients with a blood haemoglobin(Hb)<10g/dl, and group II comprised 20 patients with a Hb>10g/dl after long-term human recombinant erythropoietin(rHuEpo) treatment. Results Plasma concentration of LPO is significantly higher (P<0.01) in all 32 HD patients than in healthy control, and SOD of HD patients is lower than health control (P=0.005). After treatment Hb concentration of group I is less than that of group II,after treatment patients of Group I has significantly higher plasma level of LPO than patients of Group II (P<0.001), SOD of Group patients I is significantly lower than that of Group II (P=0.001). An inverse correlation is seen for LPO and Hb (r=-0.680, P<0.001), a positive correlation is also seen for SOD and Hb (r=0.449, P=0.01). Conclusion The oxidative stress product of uremic patients is greater than that of the normal controls, which proves that the oxidative stress of uremia increase. Hb of group I is lower than that of group II,demonstrating that oxidative stress increases with the decrease of Hb concentration. There is a positive correlation between renal anemia and oxidative stress. Correcting renal anemia effiently is very effective to decrease the oxidative stress.