The aim of the present work is to prepare and characterize carboxylated latexes (CLs) in order to bind antibodies covalently and efficiently. Carboxylated latexes were prepared by surfactant-free emulsion polymerization using an ate-initiator, which provides carboxyl end groups on the latex surface directly. Two latexes were characterized using different techniques : particle size by electron microscopy and photocorrelation spectroscopy, surface charge density by conductimetric and potentiometric titrations, and electrophoretic mobility versus pH and ionic strength (KBr). The colloidal stability of both latexes shows that these carboxylated latexes can be used for biomedical applications. Activation of carboxyl end groups was performed using the carbodiimide method, and the best conditions for covalent coupling of IgG were obtained.