Epoxy resin mixtures suitable for producing halogen-free flame-retardant composites by the injection process comprise the following components: (A) a phosphorus-free aliphatic and/or aromatic and/or heterocyclic epoxy resin; (B) an epoxide group-containing phosphorus compound; (C) a phosphorus-modified epoxy resin with an epoxide value of from 0.02 to 1 mol/100 g, obtained by reacting polyepoxy compounds having at least two epoxide groups per molecule with phosphinic anhydrides and/or phosphonic anhydrides or with phosphonic monoesters, followed by thermal elimination of alcohol; and (D) as hardener, at least one primary or secondary aliphatic polyamine with NH and/or NH2 groups.