The invention provides thiazole derivatives of the general formula I: ##STR1## or acid-addition salts or metal salt complexes thereof, in which R represents an optionally substituted phenyl group; A represents a group ##STR2## R.sup.1 represents a hydrogen atom or an optionally substituted alkyl, alkenyl or aralkyl group; and R.sup.2 represents a hydrogen or halogen atom or an alkyl, haloalkyl, alkoxy, haloalkoxy, alkylthio, hydroxyl, cyano, nitro, amino, alkylamino or dialkylamino group; processes for their preparation; compositions containing such compounds and their use as fungicides.