Results concerning the copolymerization of styrene with isoprene and maleic anthydride by vibratory milling are presented. The influence of some mechanochemical parameters (size of the grinding bodies, filling ratio, vibratory amplitude), on the conversions degree is discussed. In order to elucidate the mechanism, the syntheses of the copolymers were carried out in argon, nitrogen and carbon dioxide, and compared with the results in vaccum.