This paper presents the results of an investigation into the effect of oscillatory flow in a membrane-based affinity contactor. This device was designed to accommodate a tubular affinity membrane, and the flow direction of working fluid was tangential to the surface of the membrane. Cibacron Blue F3G-A was utilized as the capturing ligand and bovine serum albumin as the target molecule. The dye molecules were immobilized covalently via spacer molecules (polyethylenimine) onto the pores of a microfiltration membrane with a pore size rating of 0.45 mu m. Bovine serum albumin was pumped through the annular space between the concentric screw-threaded insert and the tubular membrane in oscillatory flow with a mean flow component. The effects of pulsation frequency and stroke length were investigated. It was found that, as a result of the pulsatile flow, the protein recovery was increased by a factor of 2. To make the interpretation of the results easier, various dimensionless groups were defined specifically for this system and the experimental data were reported in terms of these groups.