A new method of calculation of protein adsorption on polymeric surfaces is presented. The method considers the thermodynamic equilibrium of a three-component system--water, protein, and polymer surface--and describes the protein concentration profile based on the interaction energy parameters for protein-polymer, water-polymer, and protein-water contacts. Calculation of these parameters calls for introduction of the energies arising from the dispersive forces, the hydrophobic effect, and the Drago et al. (1971) electron donor-acceptor interactions. Comparison with experimental results of protein adsorption on various polymeric surfaces gave satisfactory agreement.