Objective To elucidate the biocompatibility differences of 4 dialyzers with different membranes in maintenance hemodialysis (MHD)patients. Methods A total of 60 MHD patients were enrolled in the prospective,randomized,control,cohort study.In baseline,synthetic polysulfone(PS)membrane dialyzer was used in all the patients for at least 3 months.Then the patients were randomly divided into three groups:ployethersulfone(PES)membrane group,cellulose triacetate (CTA)membrane group,and synthetic polymethylmethacrylate(PMMA)membrane group.Study duration was 6 months.No dialyzer was reused.The biocompatibility markers were detected repeatedly at different time points and compared with each other in different dialyzer groups. Results The blood levels of high sensitive C reactive protein,interleukin-1β and interleukin-13 were not significantly different among different groups on every time point.However,the blood complements levels and WBC count were significantly different among four kinds of dialyzer.When the dialyzers changed from PS to PMMA membrane,C3a levels and WBC count changed significantly(P＜0.05).Moreover,the change of C5a level was significantly different between PES group and PMMA group on month 3(P＜0.05). Conclusion There are some differences of biocompatibiliy among different dialyzer membranes.