Fiberfill fibers are treated with aqueous dispersions of organopolysiloxanes obtained by reaction of condensation-curable organopolysiloxanes with silanes (R.sup.3O).sub.3SiCR.sup.2.sub.2--Y or their hydrolyzates, where R.sup.2 is hydrogen or a monovalent lower alkyl radical, R.sup.3 is an alkyl radical, Y is --NHR.sup.4, --NR.sup.4.sub.2 or --NR.sup.5 in the presence of water, emulsifier and optionally further silanes (R.sup.3O).sub.xR.sub.3-xSi--R.sup.6-Z or their hydrolyzates, where R.sup.6 is a divalent C.sub.2-18 hydrocarbyl radical and Z is an amino or aminoalkylamino, epoxy, or (meth)acryloyloxy radical, and x is 1, 2 or 3, and optionally further materials which do not take part in the reaction, wherein no metal-containing catalysts are used and that the organopolysiloxanes and silanes are used in such amounts that the organopolysiloxanes, after removal of water, form elastomeric films insoluble in toluene.