Silibinin (SLB) is a plant extract with antioxidant, anti-inflammatory, and cytoprotective effects that has received much attention in the last decade. SLB-modified polysulfone (PSF) hemodialysis membranes have been fabricated using an immersion phase transformation method. The antioxidant properties of the membranes were evaluated in terms of their 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonate) (ABTS(+)) free radical scavenging activities and lipid peroxidation inhibition. The antioxidant stability of the PSF/SLB blend membranes was investigated under typical hemodialysis conditions and preserved for 90 d avoiding light. The blood compatibility of the membranes was also studied. The results showed that, with increasing SLB content, the antioxidant properties and the stability of free radical scavenging rate of the blend membranes were improved. Furthermore, red blood cells and platelet adhesion, and superoxide dismutase (SOD) levels, were decreased using the PSF/SLB membranes. The results indicated that modification with SLB afforded PSF membranes with good antioxidant properties for practical applications. These new PSF/SLB blend membranes are expected to be applied to hemodialysis to reduce the oxidative stress in patients.