The molecular electrostatic potentials (MEPs) of artemisinin (also known as qinghaosu), yingzhaosu A, and some synthetic analogues have been calculated and studied as a means of distinguishing between high and low antimalarial activity. To facilitate comparison, the dimensionality of the MEP was reduced by Kohonen Neural Network transforms. The reduction revealed that peroxides exhibiting high antimalarial activity are characterized by a continuous strip of negative electric potential surrounding the molecule, whereas peroxides of lesser activity show a broken strip.