While good oil-repellency can be imparted to fibre materials by treating them with polymers containing perfluoralkyl groups, it is difficult to impart water-repellency to the fibre materials at the same time and also give the treated materials a good handle. This is achieved by treating the fibre materials with, besides the perfluoralkyl group-containing polymers, an addition product of a) an unsaturated compound which is an olefin, a vinyl or allyl ester of an aliphatic straight or branched chain acid, a vinyl ether whose alkyl radical has at least 4 carbon atoms, an allyl ether whose alkyl radical has at least 4 carbon atoms and/or a vinyl halide with b) an organopolysiloxane which contains hydrogen atoms bonded to silicon atoms, the addition product containing on average more than 7 carbon atoms in the alkyl radical and at least 0.20 mole of the unsaturated component a) per gram atom of hydrogen in the siloxane component b).