An elastomer composition based on at least one diene elastomer, an inorganic filler as reinforcing filler, a polyfunctional organosilane as (inorganic filler/diene elastomer) coupling agent bearing at least two functions denoted "X" and "Y" which are graftable, on the one hand, to the elastomer by means of the X function and, on the other, to the inorganic filler by means of the Y function, characterized in that said Y function is a hydroxysilyl function (.ident.Si--OH). Preferably, this organosilane is a hydroxysilane polysulfide, the diene elastomer is selected from the group consisting of polybutadienes, natural rubber, synthetic polyisoprenes, butadiene copolymers, isoprene copolymers and the reinforcing inorganic filler is a siliceous or aluminous filler of the highly dispersible type. Tires or semi-finished products for tires, in particular treads for tires comprising a composition according to the invention.