Equilibrium between ion exchangers and proteins is one of the most important factors in ion exchange chromatography. A model system was used to simulate the adsorption of human serum albumin (HSA) and ovalbumin (OVA) as a binary protein system to the DEAE Sepharose FF as an anion exchanger. Two models, one based on a competition between adsorbing molecules and the other a non competitive model have been compared to experimental results. Competitive adsorption was seen in experiments in which breakthrough curves and the profiles of adsorbed proteins in packed beds were determined. However, although the results for packed bed experiments were more closely predicted by the competitive model, some discrepancies were found, suggesting that when considering multicomponent protein adsorption to ion exchangers it may also be necessary to take account of factors such as the molecular size of adsorbing proteins and any potential inter protein interaction, which may hinder the development of a general model of multicomponent protein adsorption to ion exchangers.