A method for affinity membrane column design, based on the analytical solution of the Thomas model for frontal analysis in membrane column adsorption, was developed. The method permits to find the operating conditions to reach a 93.5% of the column capacity as operating capacity, using a sharpness restriction for the system breakthrough curve. The solution of the model is presented in a graphic form and can be used in a wide range of operational conditions, provided that four design restrictions are fulfilled. The application of the method was illustrated using experimental data and a simple procedure. The implications of the results on the design and optimization of affinity membrane chromatographic columns are discussed.