One of the big success stories in synthetic biology is the re-engineering of an existing organism to produce the anti-malarial drug artemisinin. The drug is also found naturally in extracts of the plant Artemisia annua (Wormwood), but demand is far oustripping supply and extracting the drug from the plants is complex, time-consuming and expensive. In this lecture, Jay Keasling describes how he and his laboratory re-designed yeast microbes into living mini anti-malaria drug factories producing artemisinin more cheaply and efficiently. The lecture was given at the 12 May 2009 launch of the Imperial-based Centre for Synthetic Biology and Innovation—established in partnership with the London School of Economics and funded by the Engineering and Physical Sciences Research Council (EPSRC) as part of a science and innovation award.