When AIDS first appeared in San Francisco, nobody knew that it was caused by a virus. However, there was a strong suspicion that the disease could be transmitted by sexual contact. Fortunately, several years earlier, in 1977, gay physicians living in the city had already formed a medical association of their own, the Bay Area Physicians for Human Rights (BAPHR). The members, being familiar with the sexual habits of San Francisco’s gay population, were able to develop and promote the first effective prevention strategy - the “Safe Sex Guidelines”. Another important step was the creation of a special organization, the San Francisco AIDS Foundation, which started many innovative prevention programs. Supported by the gay community at large, the city closed its “gay bath houses”, where apparently many infections had taken place. As an alternative, the community developed various “safe sex clubs”. The San Francisco General Hospital set up a model ward for those who had fallen ill, and a new private organization, Shanti, devoted itself to the care of sick and dying patients. In short, San Francisco set an early example on how to combat the growing epidemic, and this example was followed in most Western countries.