Folk medicine is often a rich source of leads for discovery of valuable new drugs (1). Quinine was discovered this way, based on traditional medicinal use of the bark of the Cinchona tree, and the powerful anticancer drug taxol was discovered in Yew trees. Chinese folk medicine has now led to isolation, identification, and clinical use of artemisinin (qinghaosu, 1) (Scheme I), a sesquiterpene 1,2,4-trioxane lactone, for rapid and effective chemotherapy of individuals infected with Plasmodium falciparum malaria parasites (2).