In order to decrease their hydrophobicity and thus to reduce the protein adsorption at their surface, polystyrene-divinylbenzene (PS-DVB) particles have been coated with dextran. To favor its adsorption, the polysaccharide was previously substituted with low concentrations of phenoxy groups. The amount of dextran adsorbed onto the PS-DVB surface was examined as a function of the polymer concentration, and various samples of beads, differing in surface dextran concentration, were prepared. The adsorbed polymeric layer was then chemically cross-linked and its stability was checked in the presence of sodium dodecyl sulfate. The hydrophilic character of the various resulting beads was evaluated toward the adsorption of bovine serum albumin, a strongly hydrophobic protein. By this study, the conditions for coating polystyrene particles were optimized and the dextran layer was shown to greatly reduce the nonspecific adsorption of proteins.