Recent molecular studies point to the unorthodox conclusion that malaria parasites have a photosynthetic ancestry. Coupled with other phylogenetic evidence, this finding may apply across the phylum Apicomplexa, including other important pathogens such as the coccidia and piroplasms. We propose that an organelle corresponding to a residual plastid, performing unknown functions, is likely to reside in all, or many, of these organisms. The new findings discussed here highlight once more the pressing need to discover more about the basic biology of these economically important parasites. From such knowledge, new targets for chemotherapy may be identified.