HIV testing among substance abusers in the United States is a significant public and individual health issue in need of further examination. We analyzed interview data gathered over 15 months in 1992 and 1993 from 2315 patients on presentation for addiction treatment to determine the frequency of and factors associated with previous HIV testing. Among this group of alcohol, heroin, and cocaine abusers, 53% (1231) reported previous HIV testing. Although in bivariate and multivariable analyses those with identifiable risk factors for HIV were more likely to have been tested, 27% of injection drug users, 38% with multiple sexual partners, and 39% of those with a history of a sexually transmitted disease (STD) had not been HIV tested. Other factors associated with previous HIV testing included having a primary care physician, the primary care physician's awareness of the patient's substance abuse problem, and having received prior addiction care. However, 38% of substance abusers who had previously received addiction treatment beyond detoxification had not been tested. Of those tested, 10% (n = 122) reported a positive test, and 7% (n = 81) had not received the test results. Of those with positive test results, 37% were not injection drug users. Promotion of HIV testing among alcohol and other drug abusers in both medical and substance abuse treatment settings should be a priority.