The wetting by water of adsorbed layer of β-casein on hydrobised silica and pure (hydrophilic) silica surface was investigated by dynamic contact angle measurements based on the Wilhelmy plate principle. The results are discussed in relation to adsorption studies on similar surfaces using in situ ellipsometry. The results show that adsorbing β-casein to a hydrophobic surface lead to a significant decrease of the contact angle in particular in terms of the receding contact angle, for which a decrease of about 70 degrees was observed. This indicates a strong shielding of the hydrophobic surface by hydrophilic β-casein groups. Adding a specific enzyme, endoproteinase Asp-N, which previously have been proposed to remove a large fraction of these segments, results in a significantly decreased wettability of the solid surface. The layer is now more hydrophobic and the hysterises is much smaller. The receding contact angle after the proteolysis is roughly 70°. The results are consistent with the hypothesis that β-casein adsorb at hydrophobic surface to form a monolayer with the hydrophobic part of the protein anchored at the surface, leaving the hydrophilic segments dangling into the solution. On the hydrophilic surface, less dramatic effects are observed in terms of changes of the wettability. The surface is still quite hydrophilic both after adsorbing β-casein and exposing the layer to endoporteinase Asp-N. These results confirm previously discussed differences in the structure of β-casein layers on the hydrophobic and hydrophilic surface.