People fifty years or older now account for the majority of AIDS cases in San Francisco, California, 2010.

People aged 50 and older are an increasing proportion of the population of persons living with AIDS (PLWA) in the USA. We used San Francisco's population-based HIV/AIDS surveillance registry to examine trends in the age distribution of people diagnosed and living with AIDS in San Francisco, California. AIDS case reporting is highly complete. Death ascertainment is complete through 2009 and 95% complete for 2010. At the end of 2010, 9796 persons were living with AIDS in San Francisco. Of these, more than half (5112 or 52%) were 50-years old or older. This proportion has steadily increased since 1990 in San Francisco. Our data also indicate that age at AIDS diagnosis has increased in San Francisco during the years 1990-2010. The proportion of PLWA who are aged 50 years or older is now a majority among PLWA in San Francisco. We believe that San Francisco is the first local jurisdiction in the USA to reach this milestone. The growing population of older persons with AIDS presents new challenges for research, medical care and support services.