Analyses of the responses to the National Center for Health Statistics' AIDS Knowledge and Questionnaire revealed few differences in knowledge about modes of transmission, uncommon sources of infection, and preventive measures between IVDUs who are at high risk for HIV-1 infection and the general public, presumed at low risk of HIV infection. Further analyses of HIV-1 and AIDS knowledge demonstrated no differences on the basis of HIV-1 serostatus or awareness of serostatus, with the exception that those aware of their serostatus were less likely to report hopelessness than those who were unaware of their serostatus. With respect to comparisons of high and low risk drug behaviors, no important differences were found for levels of knowledge. However, IVDUs reporting a prior history of treatment for drug abuse demonstrated systematically higher levels of knowledge about routes of transmission and prevention methods compared to IVDUs with no treatment history. On the other hand, IVDUs with a history of treatment perceived themselves at greater risk of infection. These data demonstrate the dissemination of knowledge about HIV-1 infection to the IVDU community. Increasing treatment opportunities may provide a route for assistance with behavior modification for this group. 1 figure, 5 tables, 1 note, and 15 references