Objective To quantitatively compare the effects of bleach and peracetic acid reprocessing on the clearance and surface charge characteristics of Fresenius F80B polysulfone dialyzers. Methods Clearance experiments were performed using urea, vitamin B_12, and polydisperse dextrans in an in vitro dialysis circuit. Clearance, ultrafiltration coefficient and zeta potential were obtained on a new F80B dialyzer, after exposure to plasma in a 3 h in vitro dialysis session, and after cleaning with bleach and peracetic acid.Results Bleach was able to remove the protein deposit, restoring the clearance characteristics, but there was a significant increase in the net negative charge of the membrane due to chemical reaction with the bleach. In addition, longer time exposure to bleach altered the membrane transport characteristics, increasing the solute clearance. Dialyzers cleaned with peracetic acid had significantly lower clearance of the larger dextrans due to the presence of residual protein on or within the membrane. Conclusion Cleaning with bleach and peracetic acid may have dramatically different effects on the clearance and surface charge characteristics of F80B polysulfone dialyzers.