Furoxan derivatives bearing a sulfone moiety at position 3 or 4 were synthesized and tested for their antimalarial action on the chloroquine-sensitive D10 and the chloroquine-resistant W2 strains of Plasmodium falciparum. The furazan analogues were considered for comparison. The most active compounds were the products in which the -SO2R groups are at the 3-position of the furoxan system. These latter substances displayed an antimalarial activity in the microM range, possibly related in part to their ability to release NO.