Objective To study whether the apoptosis of peripheral blood mononuclear cells (PMBC) can be used as an index to evaluate the biocmpatibility of hemodialysis membranes. Methods PMBC of hemodialysis patients were stimulated in vitro with different biocompatibility membranes for 0 to 72 hours, then Flow cytometry and ELISA analysis were applied to evaluate the apoptosis and the synthesis of interleukin-1 and tumor necrosis factor- of PMBC. Results Bad biocompatibility membrane such as CA membrane can cause much heavier apoptosis of PMBC than good biocompatibility membrane can do, the absorbent density (OD) which represents the degree of PMBC apoptosis in CA group was significant higher than that in PS group and control group. In CA group, OD in 48 hr was significantly higher than that in 24hr and it had no significant different with OD in 72 hr (P>0.05). Our data also showed that the apoptosis of PMBC had a significant positive correlation with the production of interleukin-1 and tumor necrosis factor- during which they were stimulated. Conclusion It is advisable to use the apoptosis of PMBC as an index to evaluate biocmpatibility of hemodialysis membranes.