Compositions for the oxidative dyeing of keratin fibers, comprising a medium suitable for dyeing and at least one bicyclic 5-6 systems of aza heteroaromatic keratin dyeing compounds wherein the 5-membered rings have one to three nitrogen atoms and an N-hydroxy or N-amino group and derivatives thereof. A method for oxidative dyeing of keratin fibers, comprising applying such compositions in the presence of an oxidizing agent, for a period sufficient to develop the desired coloration.