【Abstract】Objective To assess the transfer of endotoxin across cellulose triacetate (CTA, low-flux) and polysulfone (high- or low-flux) membranes. Methods Three groups based on the dialyzer of different membrane and flux were used in this study. Experiments were carried out in saline-saline model. The dialysate was contaminated with purified lipopolysaccharide (LPS) (2EU/ml, 10EU/ml or 20EU/ml). Samples were drawn from blood side and dialysate outflow every 1 hour during dialysis process. Endotoxin level was detected by kinetic turbidimetric LAL method. We compared the decrease degree of endotoxin in dialysate among groups.  Results All blood side samples were LAL negative after 4-hour dialysis. Endotoxin concentration in dialysate decreased along with dialysis time, and F60S was significant faster than 130G in decrease degree of endotoxin in dialysate (59.99±13.68% vs. 83.37±9.14%, P=0.036).  Conclusion Within the limit of 20EU/ml in dialysate, no transfer of endotoxin was observed across high-/low- flux polysulfone and low-flux CTA dialyzers. Polysulfone high-flux dialyser has an advantage of endotoxin absorbility more than CTA low-flux dialyser. No significant difference was observed between high- and low-flux polysulfone dialysers.