Good antischistosomal activity is shown by nitrofurylvinyl derivatives such as amides of 3-(5- nitro-2-furyl) acrylic acid (4b and 5b), as well as by nitrothiazole derivatives such as niridazole (la). The effects of interchanging the nitroheterocyclic groupings have been studied by the synthesis and biological comparison of five pairs of exact analogs. Replacement of nitrofuran by nitrothiazole in the nitrofurylacrylic acid amides (4b and 5b) ...