The effect of polyacrylonitrile-g-poly (vinyl alcohol) (PAN-g-PVA) copolymer additive on the properties of PAN-based hollow fiber UF membranes was studied. The resulting hollow fiber membranes were characterized with respect to structural morphology, surface properties, and proteins rejection in order to investigate the impact of PAN-g-PVA copolymer composition (presented at different PAN: PAN-g-PVA ratio) in the UF membrane on the separation and antifouling properties. Results showed that the hollow fiber membrane prepared from the highest composition of PAN-g-PVA copolymer (PAN: PAN-g-PVA 80 : 20) was able to produce pure water flux as high as 297 L/m2·hr in comparison to 41 L/m2·hr reported in control PAN membrane when tested at 1 bar. Fouling experiments performed using bovine serum albumin (BSA), albumin from chicken egg (CE) and trypsin indicated that the blend membranes with higher surface coverage of hydrophilic PVA (34-60%) were more excellent in minimizing protein fouling, which might be correlated with the formation of hydrophilic PVA layer on their surface. Although increase in membrane hydrophilicity upon PAN-g-PVA copolymer incorporation might be the main reason contributing to improved membrane antifouling properties, the changes in membrane surface roughness and pore size could not be completely ruled out to influence membrane anti-fouling resistance during protein filtration.