Abstract: The invention relates to a polymer mixture which comprises an aromatic polycarbonate, a styrene-containing copolymer and/or a styrene-containing graft polymer and a given type of polysiloxane-polycarbonate block copolymer. It has been found that the use of this given type of polysiloxane-polycarbonate block copolymer leads to a polymer mixture having improved impact strength properties. The polysiloxane-polycarbonate block copolymer used is built up from(a) 1-50% by weight of polysiloxane blocks of formula II and(b) 50-99% by weight of polycarbonate blocks of formula III, wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4, R.sub.5 and R.sub.6 each independently of each other represent a hydrogen atom, a hydrocarbyl or a halogenated hydrocarbyl, D is an integer from 5-140, Y is a hydrogen atom or an alkoxy, and wherein A is a bivalent hydrocarbon group having 1-15 carbon atoms, which bivalent hydrocarbon group may be substituted, is an --S--; an --S--S--; an --S--(O)--; an --S(O).sub.