The invention relates to a novel process for preparing chloromethylpyridines of the general formula (I) ##STR1## in which n represents the numbers 0,1,2 or 3 andX represents halogen,by reacting aminomethylpyridines of the general formula (II) ##STR2## with a nitrosating or diazotizing agent in the presence of a diluent and optionally in the presence of hydrogen chloride at temperatures between -20.degree. C. and +50.degree. C. and then working up in a conventional manner.