Abstract: The expression of process kinetics of protein adsorption in a hollow fiber affinity membrane has been established through analysis of the flow distribution and adsorption reaction.The process of human Y-immunoglobulin adsorption onto an immobilized protein A hollow fiber membrane was taken as an example.Homogeneous binding of uniform sites with the same reaction constant and heterogeneous binding of two different sites with different reaction constants have been considered.Breakthrough curves are obtained through numerical solution of the partial differential equations by finite difference method.The comparison between the predicted curves and the experimental curves showed a better agreement for the heterogeneous binding model.