The present update to the data base incorporates all available epidemiological information for developing countries presented at the 5th International Congress on AIDS in Asia and the Pacific, Kuala Lumpur, 1999, and XI International Conference on AIDS and STDs in Africa, Lusaka, Zambia. Currently the HIV/AIDS Surveillance Data Base contains over 53,139 individual data records drawn from 5,065 publications and presentations. It is our goal to incorporate all available data from seroprevalence studies conducted in developing countries.