5-Alkoxyalkyl-6-alkyl-7-aminoazolopyrimidines of the formula I in which the substituents are defined as follows: R1 is alkyl, cycloalkyl, alkenyl, alkynyl, alkoxyalkyl, cyanoalkyl, and benzyloxyalkyl, where the groups in the aliphatic or aromatic moiety may be unsubstituted or may have substitution by from one to three groups Ra: Ra is halogen, cyano, nitro, hydroxy, cycloalkyl, alkoxy, alkylthio, and NRARB; RA, RB are hydrogen and alkyl; R2 is alkoxyalkyl, phenoxyalkyl, alkylthioalkyl, and phenylthioalkyl, which groups may have no substitution or may have substitution according to the description; R3 is hydrogen and alkyl; A is N and C—RA; processes for preparation of these compounds, compositions comprising them, and their use for controlling phytopathogenic harmful fungi.