Thirty-two N-allylamino acids were prepared, and their preventive activity against Fusarium diseases was determined. Esters of N-allyl-glycine and -sarcosine showed a strong effect in preventing yellows of the Japanese radish caused by Fusarium oxysporuwn f. sp. raphani. These compounds were also effective against Fusarium wilt of tomato by foliage treatment. The preventive activity of N-allylsarcosinates varied insignificantly with the variation of the alcohol moiety of the esters. Although n-dodecyl N-allylsarcosinate was shown to effectively control Fusarium diseases, it did not affect the growth of Fusarium on an agar medium. The preventive effect was dependent on the application time. Enhancement of the peroxidase activity and the accumulation of total phenols were seen in the plants treated with these chemicals.