Our laboratories have been investigating biological effects of a sesquiterpenoid polygodial and its natural and synthetic analogues. Herein, we report the evaluation of these compounds against the three forms of <i>Trypanosoma cruzi,</i> amastigotes, trypomastigotes and epimastigotes. Although polygodial was found to be poorly active, its natural congener epipolygodial and synthetic Wittig-derived analogues showed low micromolar potency against all three forms of the parasite. Synthetic α,β-unsaturated phosphonate <b>9</b> compared favorably with clinically approved drugs benznidazole and nifurtimox, and was effective against trypomastigotes, toward which benznidazole showed no activity.