To determine whether AIDS surveillance misses a substantial number of persons who die with unreported AIDS, we conducted a cross-sectional survey of decedents examined by the San Francisco (SF) Medical Examiner. Decedents who received toxicology screening were tested for HIV antibody and examined for evidence of AIDS. Names of decedents with positive or indeterminate HIV antibody test results were cross-referenced against the SF AIDS registry to identify previously reported AIDS cases. Medical records of unreported cases were reviewed to determine whether AIDS had been diagnosed prior to death. Of 1959 decedents tested, 176 (9%) were HIV positive; 105 (60%) were identified as having AIDS by the Medical Examiner. Of the 105 AIDS cases, 101 (96%) had been previously diagnosed; 98 (97%) had been previously reported. Overall, diagnosis and reporting were 93% complete. HIV-infected decedents were more likely than those uninfected to be men and <45 years old, and less likely to be Asian/Pacific Islander or Native American (p <.001). They were more likely to have died of suicide (p <.05) or drug abuse/overdose (p <.001). In SF, AIDS case reporting is highly complete. Current surveillance activities, which identify cases from health care settings, are appropriate. To decrease deaths among HIV-infected persons, suicide prevention and substance abuse treatment programs are needed.