Process for manufacturing vinyl-aromatic polymers reinforced with rubber and with bimodal morphology of the rubber phase, which process comprises:blending a first stream of a first vinyl-aromatic prepolymer, containing a fine-particle rubber phase prepared in a reactor of PFR type, with a second stream consisting of a larger-particle prepolymer, prepared in a CFSTR (Continuous Flow Stirred Tank Reactor);completing the polymerization until a rubber-reinforced vinyl-aromatic polymer with bimodal morphology is obtained, which is characterized by a considerable improvement in mechanical synergism associated with excellent aesthetic properties.