Previous reports have shown antisocial personality disorder (ASPD) to be strongly associated with injection equipment sharing and increased rates of human immunodeficiency virus (HIV) infection in a sample of heroin injectors. Another report has shown ASPD to be associated with injection drug use, needle sharing, sexual promiscuity, and prostitution in a sample of methadone maintenance clients. The current study extends this work by examining the relationship of ASPD and human immunodeficiency virus (HIV) risk behaviors in a sample of cocaine users (48% out of treatment and 52% just entering treatment). Associations were tested for sexually risky behaviors in addition to injection behaviors. The principle finding of this study is that ASPD was shown to be associated with increased rates of injection drug use and sharing syringes, with earlier age of onset of injection drug use, with certain venereal diseases, and with a variety of HIV risk sexual behaviors. When men and women were tested separately, the pattern of association of risky behaviors with ASPD varied considerably. Overall, this work confirms that psychiatric status, especially the presence of ASPD, may have to be considered in evaluating the results of HIV risk-reduction interventions.