Objective To evaluate intradialytic blood pressure variability (BPV) in patients on maintenance hemodialysis (MHD),and to investigate the correlated factors of BPV in MHD process and its correlation with prognosis.Methods Patients with end stage renal disease on MHD before January 1,2009 were enrolled and analyzed retrospectively.Blood pressure at the first hemodialysis every quarter during January,2009 and December,2010 were recorded.The systolic pressure,diastolic pressure were calculated,and dialysis systolic and diastolic BPV were expressed with discrete coefficients.As for patients with follow-up time less than 2 years,blood pressures in evenly distributed 6-8 courses were used for calculation.Cardiovascular events and death were recorded and the follow-up was lasted till December 31,2011.Results A total of 280 patients were enrolled,with intradialytic systolic BPV of 0.119 ± 0.029,and intradialytic diastolic BPV of 0.118 ±0.028.Intradialytic systolic BPV in the elderly group (n =114) was significantly higher than that in the younger group (n =166) (0.126 ± 0.029 vs 0.114 ± 0.028,P =0.012),while no significant difference was found in diastolic BPV (0.117 ±0.031 vs 0.119 ±0.025,P =0.498).Intradialytic systolic BPV was used as variates in multivariable regression analysis,and results showed that age,systolic blood pressure before dialysis,interdialytic weight gain (IDWG) rate during dialysis and hemoglobin level were independent influential factors for intradialytic systolic BPV.The intradialytic diastolic BPV was used as variates in multivariable regression analysis,and results showed that IDWG rate and average dehydration volume were independent influential factors for intradialytic diastolic BPV.During 3 years of follow-up,64 patients died (22.9％).The survival analysis showed that the dialysis systolic BPV elevation was associated with the mortality rate (P ＜ 0.01).Conclusions Older age,high systolic pressure before hemodialysis,high IDWG rate,and low hemoglobin level were independent risk factors of high intradialytic systolic BPV increase.Intradialytic high IDWG is an independent risk factor of high intradialytic diastolic BPV increase in patients on MHD.Intradialytic systolic BPV increase is associated with all-cause mortality in patients on MHD.