Objective To study the concentration of plasma total homocysteine(tHcy) in patients with chronic renal failure(CRF).Methods 105 chronic renal failure patients and 35 health individuals to our hospital were chosen to measure the level of tHcy using enzymatic cycling assay method.Results The mean level of tHcy in renal failure period C RF patients was significantly higher than that in normal controls (t =3.12,P ＜ 0.05),and the level of plasma tHcy was significantly higher in Uremia stage than in renal failure period in CRF patients (t =6.41,P ＜0.05),and the level of plasma tHcy was significantly higher in renal failure period than in renal function decompensated period in CRF patients (t =11.27,P ＜ 0.05).Conclusion The level of plasma tHcy were significantly elevated in patients with CRF,and there is a trend that the level of plasma tHcy increases with severity of CRF.Serum tHcy concentration have significant value in the diagnosis and understanding the condition of patients with CRF.