Abstract: A novel hydrophilic anionic charge modified microporous filter membrane is provided comprising an organic polymeric microporous filter membrane having a micro-structure throughout the membrane and a modifying amount of an anionic charge modifying agent bound to substantially all of the membrane micro-structure without substantial pore size reduction or pore blockage.The invention is further directed to a process for anionically charge modifying an organic polymeric microporous filter membrane by applying to the membrane the charge modifying agent, preferably, by contacting the membrane with a solution of the charge modifying agent.The anionic modified microporous membrane of this invention may be used for the filtration of fluids, particularly parenteral or biological liquids contaminated with charged particulates, and for plasmapheresis, particularly in the form of hollow fiber tubes. The membrane has low extractables and is sanitizable or sterilizable.