This study analyzes the effect of transmembrane pressure pulsing on transient steric hindrance for BSA ultrafiltration in an unstirred batch cell using 100,000 MWCO cellulosic membranes. Studies were performed with fresh membranes and membranes preadsorbed with 0.1% IgG for 0.5, 2.25 and 26 hours. The Kedem-Katchalsky model was used to determine the apparent sieving coefficients and estimate the wall concentrations. Hindered transport theory was used to estimate the resulting apparent pore size of the membranes for pulsed and nonpulsed cases. The apparent pore size was increased by 8% when pulsing was used in conjunction with fresh membranes. The intrinsic sieving coefficients were increased by 33% during pulsing. Pulsing also substantially increased the apparent pore size and the initial sieving coefficients for the IgG preadsorbed membrane cases. Based on the initial time data for the IgG preadsorbed membrane cases, it was determined that the presence of IgG on the membranes could affect the concentration of BSA in the permeate. It was also found that transmembrane pressure pulsing could partially eliminate this resistance to BSA permeability.