It is known some proteins can disaggregate endotoxins and form complexes with lipopolysaccharide (LPS). Nevertheless, how protein concentration affects protein-LPS binding and endotoxin removal is unknown. In this study, protein samples at various concentrations were incubated with endotoxin samples at a fixed concentration. The mixtures were filtered by ultrafiltration membranes. As protein concentration increased, the amount of endotoxin detected in the filtrates increased too. This result indicates protein concentration has significant effect on protein-LPS binding and the amount of endotoxin disaggregated.