Abstract: In the production of an aryl lactamhydrazone of the formula ##SPC1##In whichA represents optionally substituted alkylene, aralkylene or cycloalkylene, each with up to 20 carbon atoms, andQ represents optionally substituted, mononuclear to trinuclear aryl or an optionally alkylsubstituted mononuclear or binuclear heterocyclic aromatic system with 1 to 3 hetero atoms,In which a lactim-ether of the formula ##SPC2##In which R is aryl or alkyl of 1 to 6 carbon atoms,Is reacted with an arylhydrazine or heteroarylhydrazine of the formulaH.sub.2 N--NH--Q (III)the improvement which comprises effecting the reaction at a temperature of about -20.degree. to 150.degree.C and in the presence of at least a catalytic amount of acid, whereby the yield is markedly increased. Those compounds wherein A is --(CH.sub.2).sub.2-11 -- and Q is pyridyl or phenyl substituted by at least one nitro, sulfo, sulfonamido or carboxy group are new and exhibit fungicidal activity.