Abstract: The invention relates to a novel process for the preparation of 6-(substituted amino)-3-pyridazinylhydrazines having the general formula I ##STR1## and their pharmaceutically acceptable acid addition salts, wherein R.sup.1 stands for hydrogen atom or an alkyl group containing from 1 to 4 carbon atoms;R.sup.2 and R.sup.3 may be the same or different and stand for alkyl groups containing from 1 to 6 carbon atoms, alkenyl groups containing from 2 to 6 carbon atoms, hydroxyalkyl groups containing from 2 to 4 carbon atoms, cycloalkyl groups containing from 3 to 8 carbon atoms, phenyl or benzyl groups or phenyl, benzyl or phenylethyl groups containing one or two halogen atoms, nitro, methoxy or hydroxyl groups, and one of R.sup.2 and R.sup.3 may stand also for a hydrogen atom, or R.sup.2 and R.sup.3 together with the neighboring nitrogen atom may build up also a morpholino, pyrrolidino, piperidino, heptamethyleneimino or N-methylpiperazino group.