Attempts at modification of silica surface with a polymer ( natural latex) directly in the course of the precipitation process have been made. The effects of temperature, non-ionic surfactants and silane coupling agent in preparation of poly[ cis-isoprene]-coated silica on the precipitation of polymer/ silica composites initiated by ammonium salts (NH4Cl, (NH4)(2)SO4, NH4HCO3), have been studied. The influence of the process parameters on the quality of the silicas obtained and the character of the polymer adsorption on the silica surface has been determined along with the effect of the surface impregnation with natural latex on physicochemical parameters of the silicas ( bulk density, capacities to absorb water, dibutyl phthalate and paraffin oil) and their surface structure. (C) 2007 Elsevier B. V. All rights reserved.