Various 2-N-acyl-5-methylisoxazolone derivatives were prepared, and their antifungal activities were evaluated in vitro with mycelial growth inhibition tests. In contrast with N-alkyl derivatives, the acyl compounds showed significant activity against Pyrenophora graminea, Fusarium graminearum, Alternaria alternata, Cercospora beticola, Rhynchosporium secalis, Septoria tritici, Microdochium nivale, Rhizoctonia solani and Gaeumannomyces graminis. Of note, cinnamoyl, 3-furan-3-ylacryloyland 3-thiophen-3-yl-acryloylamides, and t-butylacetyl and pivaloyl derivatives showed high inhibition rates at 25mg/L against R. solani and G. graminis, respectively.