The adsorption and covalent coupling of bovine serum albumin (BSA) onto methylmethacrylate (MMA) based monodisperse latex particles with different hydrophylic surfaces were investigated. P(MMA) and P(MMA/HEMA) microbeads in the size range of 1.5-2.0 mum were prepared by a dispersion homopolymerization method in the presence of poly(vinylpyrrolidone) (PVP) and poly(vinyl alcohol) (PVA) as steric stabilizer and by copolymerization of MMA and 2-hydroxethyl methacrylate (HEMA) where PVP was used as steric stabilizers. Surface properties of these particles were characterized in terms of contact angle measurements and FTIR-DRS spectra. Additionally, hydroxyl groups of PMMA(PVA) and P(MMA/HEMA) particles were activated to provide aldehyde groups on surfaces. Adsorption of the BSA onto these five types of latex particles was examined as a function of initial albumin concentration, pH and ionic strength of the various cations (Na+, Ca+ and Mg+2) and anions (Cl- and SCN-). The maximum adsorption capacities for all latex particles were obtained in solutions with 0.01 mu ionic strength and 1 mg/mL BSA concentration. When using PMMA(PVA), P(MMA/HEMA) and PMMA(PVP), the adsorption increased as hydrophobicity increased. Aldehyde activation of the two most hydrophobic particles elevated the coupling (immobilization) significantly in ionic strength of 0.01 p. The adsorption and/or immobilization were maximum in the presence of monovalent cation, Na+ or anion, Cl- for all types of latex particles.