The transient surface dynamic properties of alcoholic solutions of BSA and beta-casein are studied by the longitudinal wave method over a period of 4 h. The aging effect is the most influential on the surface theology when the ethanol content is 5%, v/v. It affects mostly the apparent surface viscosity. A parametric analysis shows that the surface theology evolution is assigned to change of the residual elasticity and of the constant rate of the surface relaxation. This has been related to the protein unfolding properties and to the influence of ethanol on the protein secondary structure.