We investigated the effect of antibody solution conditions (ionic strength, pH, IgG concentration, buffer composition, and aggregate level (dimer content)) on filter performance for a virus removal filtration process using the Planova (TM) 20N, a virus removal filter. Ionic strength and pH affected the filter flux. A consistent. high flux was maintained at an ionic strength greater than 10 mM and at pH 4-8 under a typical buffer composition (sodium chloride, citrate, acetate, and phosphate). Optimum IgG concentration was 10-20 mg/mL allowing for high throughput (kg/m(2) of IgG). Dimer content negligibly affected the flux level. Under high throughput conditions, virus spiking did not affect flux whereas a parvovirus logarithmic reduction value greater than 5 was maintained. From the results of zeta potential analyses for IgG and the membrane, we considered that electrostatic interactions between antibodies and the membrane affect filter performance (flux level and throughput). These results indicate that the Planova (TM) 20N filter is applicable for a wide range of solution conditions typically used in antibody processing. (C) 2010 American Institute of Chemical Engineers Biotechnol. Prog., 26: 1080-1087, 2010