Risky behavior related to injection drug use accounts for a considerable proportion of incident HIV infection in the United States. Large numbers of injection drug users (IDUs) currently receive antiretroviral therapy in clinical settings and are accessible for risk-reduction interventions to reduce transmission of drug-resistant HIV and spread of HIV to uninfected others. The current study examined attitudes toward needle- or equipment-sharing among 123 HIV-positive IDUs in clinical care in an effort to understand the dynamics of such behavior and to create a basis for clinic-based risk-reduction interventions. Results indicate that at baseline, participants who reported extremely negative attitudes toward needle-sharing were less likely to have shared during the past month than those with less-extreme negative attitudes. Demographic, behavioral, and attitudinal variables were entered into a logistic regression model to examine needle-sharing group membership among HIV-positive IDUs. Being female and having less-extreme negative attitudes toward sharing were independent and significant correlates of sharing behavior. Interventions targeting needle-sharing attitudes deployed within the clinical care setting may be well-positioned to reduce HIV transmission among HIV-positive IDUs.