The scope of the reaction of halogen-substituted nitriles and amines was extended by including trifluoro- and dichloro-acetonitrile. Trifluoroacetonitrile reacts easily with primary and secondary aliphatic, primary aromatic, and heterocyclic amines to give the corresponding amidines. N-Mono- and N-di-substituted dichloroacetamidines were prepared from dichloro-acetonitrile and amines, Trichloroacetonitrile also affords N-substituted amidines with heterocyclic amines.