The aim of the present work is to compare the behavior of physically (passively) adsorbed and of chemically (covalently) bound IgG to carboxylated latexes (CLs), In this work we have tried to determine the advantages and disadvantages of covalent coupling of antibodies to CLs against the passive adsorption procedure. Physically adsorbed IgG was measured by direct UV spectrophotometry at 280 nm. Even when the protein has the same charge sign as its sorbent, adsorption occurs spontaneously, and this suggests an adsorption caused by hydrophobic forces. IgG chemically bound using the carbodiimide method was both directly measured using the bicinchoninic acid reaction (BCA method) and indirectly calculated using UV spectrophotometry. The covalent coupling had an efficiency rate of more than 70%. The different electrophoretic behavior shown by the IgG covalently bound to the CL particles versus that of the IgG passively adsorbed on these particles is due to the presence of the carbodiimide used in those that are chemically bound. Mobility values were dealt with using the most recent theoretical approaches, given by Ohshima and Kondo, to obtain information about the protein layer. The chemical coupling provides a better immunological response of the IgG-CL complexes.