This paper discusses three methods for obtaining information for the epidemiological surveillance of AIDS: seroepidemiological surveys among selected population groups sentinel surveillance approaches and compulsory notification of seropositives. As the experience of the AIDS Programme team of the State Secretariate of Health, Rio de Janeiro has shown, almost all available information focusses on the notification of confirmed cases. In attempt to monitor the levels and trends of HIV infection, this paper suggests that the three methods of surveillance should be used to ensure greater effectiveness in the prevention and control of AIDS.