The invention relates to a method for the production of aqueous polymer dispersions, by the polymerisation of one or more olefins in aqueous media in the presence of dispersing agents and optionally organic solvents, characterised in that the polymerisation of the olefin(s) is catalysed by means of one or more complex compounds of general formula (I), where at least one of the groups R.sup.1 to R.sup.9 must be in the form of a group of the following general formula (II) where Z=an electron-withdrawing group and n=a whole number from 1 to 5.