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The surface dilatation rheological properties of lysozyme/sodium dodecyl sulfate (SDS) mixed solutions are studied by the oscillating ring method. At the initial stage of adsorption, the rate of variations in the surface properties depends nonmonotonically on SDS concentration due to the reversal of the lysozyme/SDS complex charge with increasing degree of surfactant binding. The nonmonotonic kinetic dependences of the dynamic surface elasticity indicate the breakage of the secondary and tertiary structures of the protein in the surface layer. For lysozyme/SDS solutions, the denaturing effect of the interface appears to be stronger than for previously studied systems, namely, bovine serum albumin/dodecyltrimethylammo nium bromide and β lactoglobulin/dodecyltrimethylammonium bromide.