practical method for the regioselective halogenation of fused heterocyclicN-oxides has been developed. It employs Vilsmeier reagent, generated in situ by POX3 and DMF, as both the activating agent and the nucleophilic halide source. The method is amenable across a broad range of substrates, including quinolines, isoquinolines and the diazine N-oxides, possessing a variety of substitution patterns. Furthermore