A cohort of 111 injection drug users (IDUs) and their sex partners was assessed in 1988 concerning risk behaviors for HIV and knowledge of HIV/AIDS. Ten years later, in 1998, the cohort was reassessed using the same instrument. All who were HIV negative in 1988 were retested by blood draw for antibodies to HIV. A paired analysis was utilized to determine individual changes in risk behaviors for three serostatus groups--those who remained HIV negative (long-term HIV negatives), seroconverters, and those positive in 1988 (long-term HIV positives). Incidence was twice as high for sex partners (37.5%) as for IDUs (18.0%). Drug and needle use risk behaviors, except crack use, showed decreases; sexual risk behaviors were less amenable to change. Knowledge significantly increased among the long-term HIV negatives and seroconverters but not among those HIV positive in 1988. This analysis demonstrates the need for continued intervention among IDUs and their sex partners.