Adsorption of human serum albumin (HSA) on the particles of polystyrene suspensions with a narrow particle diameter distribution and obtained in the presence of the monomer-soluble stabilizer, di-p-tolyl-o-carbalcoxyphenylcarbinol (DTC), was studied. Values of the limiting adsorption GAMMA(max), mg/m2, for media with different pH values (4.0, 5.8, 6.8, 7.7) were determined. The binding of HSA molecules with polystyrene microspheres was shown to be maximal at pH 4 and minimal at pH 7.7. Conditions for the preparation of the latex test with maximal sensitivity were determined.