Isotactic copolymers of propene and dienes were synthesized through Ziegler-Natta catalysis and functionalized with silanes through Speier catalysis, either at one end of linear chains or at the end of short ramifications. Fibers/matrix coupling can be obtained with such polymers in one hand, through chemical bonding with the glass surface OH functions and in the other hand by cocrystallization with the poly(propylene) matrix. The grafting ability of the coupling agents (CAs) onto glass surface was studied by the sessile drop technique after solvent washing. For ramificated poly(propene)s it is possible to adjust the surface free energy with the silane content. Adhesion of the poly(propene) matrix on the sized fibers was evaluated by the microtension test. The CAs characteristics required to promote adhesion between the fibers and matrix are discussed as a function of their chemical nature and structure. The more important interfacial shear stress was obtained with poly(propene-co-8.5%methyloctadiene-g-chlorodimethylsilane) showing that a compromise must be found between the silane content and polymer crystallinity.