Abstract: Objective:To investigate the changes and clinical significance of plasma levels of nitric oxide (NO),endothelin(ET),atrial natriuretic peptide(ANP),plasma renin activity(PRA) and angiotensinⅡ(ATⅡ) before and after hemodialysis in patients with chronic renal failure(CRF).Methods:Sixty patients with CRF(30 patients with uncompensated chronic renal dysfunction and the other 30 patients with chronic renal failure) were included in the study.Thirty healthy volunteer were chosen as normal control.Blood samples were collected before and after hemodialysis.The plasma NO was assayed using colorimetry and the plasma ET,ANP,PRA and ATⅡ were determined by radioimmunoassay.Results:The plasma levels of NO,ET,ANP,PRA and ATⅡ in the group of CRF were significant higher than those of control (P<0.05 or P<0.01).After hemodialysis,plasma NO and ANP decreased significantly (P<0.05 and P<0.01) while PRA and ATⅡ increased (both P<0.01).No significant change was observed in plasma ET before and after hemodialysis.Conclusions:Plasma levels of NO and ANP can be lowered by hemodialysis therapy in CRF patients while the plasma levels of PRA and ATⅡ elevated at the same time.It's suggsted that the increase in ET may cause the rise of the concentration of ANP and PRA,and increase in concentration of ANP may inhibit the secretion of ATⅡ.