Malaria kills up to 2.7 million people a year and the death toll is predicted to double in the next two decades. In the May 23 Nature, Ito et al. describe a transgenic strategy to halt malaria by regulating transmission by mosquitoes of the Plasmodium parasites that cause the disease(Nature 2002, 417:452-455). They used the carboxypeptidase (CP) promoter that is activated by a blood meal, and CP signal sequences that direct protein secretion into the midgut lumen, to drive expression of an SMI (salivary gland- and midgut-binding peptide 1) motif. They transformed this transgene into the germline of the mosquito Anopheles stephensi. When expression of the SMI peptide was induced, it inhibited parasite development, ookinete invasion and transmission. This is the first report of transgenic regulation of Plasmodium transmission and offers a novel strategy for combating malaria.