Acylated imidazolyl-O,N-acetals of the formula ##STR1## and their pharmaceutically acceptable salts and metal complexes wherein R is alkyl, alkenyl, alkinyl, cycloalkyl, halogenoalkyl, optionally substituted phenyl, optionally substituted phenoxyalkyl, alkylamino, dialkylamino or optionally substituted phenylamino;X is halogen, alkyl, cycloalkyl, alkoxy, halogenoalkyl, alkylthio, alkoxycarbonyl, optionally substituted phenyl, optionally substituted phenoxy, optionally substituted phenylalkyl, amino, cyano or nitro; andN is 0 or an integer of from 1 to 5; are useful as antimicrobial agents, particularly for their use in treating mycotic infectins in humans and animals.