Both di- and triblock copolymers consisting of polystyrene (PS) in conjunction with poly(methylphenylsilane) (PMPS) have been successfully prepared by coupling of alpha,omega-dichloro-PMPS with poly(styryllithium). The study of this reaction has shown a sudden limitation of the coupling yield, which however depends on the PS block length. Both the polymer concentration and the solvent have also an effect on the coupling reaction. Morphology of the PS-PMPS block copolymers has been observed by transmission electron microscopy. Very complex morphologies have been reported more likely as the result of the competition between the phase separation induced by PS and PMPS immiscibility and the tendency of PMPS to form ordered structures.