To identify factors associated with unsafe needle hygiene, we studied 378 injection drug users (IDUs) in Denver, Colorado. The sample was drawn from neighborhoods with large concentrations of injectors and crack smokers. Respondents were questioned about their needle hygiene practices during the 30-day period prior to the interview. Unsafe needle hygiene, defined as injecting with previously used, nondisinfected needles, was reported by more than a third of those interviewed. Unsafe needle practices were associated with a number of factors, including heroin injection, perceived chance of getting AIDS, and lack of exposure to AIDS interventions in the community. The high percentage reporting unsafe needle practices within a 30-day interval points to the grave risk AIDS continues to pose for drug users. We conclude that the apparent success of exposure to AIDS intervention efforts in changing needle practices shows promise for prevention programs targeting drug injectors.