Blends of maleated polypropylene with maleic anhydride (PP-MAH) and maleated styrene-butadiene-styrene triblock copolymer with maleic anhydride (SBS-MAH) were compatibilized with 4,4'-diaminediphenylmethane, at various concentrations, as the coupling agent for the functionalized polymers. Their properties were compared with those of the corresponding blends of PP-MAH and styrene-butadiene-styrene triblock copolymer. The blends containing 15 and 50 wt % elastomers were prepared in a mixer at 190degreesC and 55 rpm. Torque measurements and solubility tests suggested a graft copolymerization during the melt blending of PP-MAH and SBS-MAH. Infrared spectroscopy was used to characterize the graft copolymer formed during the melt blending of the maleated polymers. The blends presented a morphology of a disperse elastomer phase in a continuous PP-MAH matrix. The size of the elastomeric domains decreased as the diamine and anhydride molar ratio increased.