A TWOFOLD lesson about science and the media emerges from a reading of the scientific and popular literature about AIDS: It’s not just that the media can, at times, misinform us about what science says; it’s also that science often speaks in an extremely qualified and hesitant manner. Not only is the AIDS epidemic extraordinarily difficult to measure, but the measurements have often been reported in misleading ways. Thus the media have not conveyed the whole truth about AIDS. But it may not be possible to arrive at that whole truth.