Objective To investigate the influence of hemodialysis membrane's biocom-patibility on serum cytokines in hemodialysis(HD) patients. Methods The serum levels of IL-12、IFN-γ、IL-4 in 26 patients dialyzed with different membranes were measured by ELISA before and after a dialysis session. Results After dialyzed with Cuprophan(Cup) membrane, the serum IL-12 levels of these patients were higher and IFN-γ levels were lower than the levels before dialyzed with Cup, P<0.05, while Polysulfone(PS) membranes and Hemophan (HE) membranes had little influence on serum IL-12 and IFN-γ levels of the patients. After HD, the three different membranes had no effects on patients' serum IL-4 levels, but the IL-4 levels of patients dialyzed with Cup membrane were lower than other groups before and after HD, P<0.01. Conclusion Hemodialysis membrane's biocompatibility has influence on levels of the serum cytokines in HD patients. This suggests that hemodi-alysis membrane's bioincompatibility may injure HD patients' immune system.