Because of their central position in people's lives, the mass media have unrivalled potential to inform and educate the general public. Yet in the response to HIV and AIDS it is generally agreed that only a tiny fraction of that potential has been tapped. There are still millions of people who have never heard about AIDS, and many more who harbour serious misconceptions about HIV infection. This study focuses on the challenges and opportunities in using the mass media in the response to AIDS and gives practical advice to those who wish to develop new projects.