Several analogues of Helminthosponum maydis race T toxin were prepared. The synthesis of the hydroxy diketones was accomplished by aldol condensations of 2-decanone with ketal aldehydes followed by deketalization. The dihydroxy ketone analogues were prepared by use of dihydroisoxazole intermediates. The analogues were tested and found to be less active than the parent toxin. The analogues still exhibited host specificity.