The authors investigated AIDS-related knowledge, high-risk behaviors, and relationships between AIDS-related knowledge, high-risk behaviors, and sociodemographic characteristics of 41 pregnant women entering treatment who were dependent on cocaine or opiates. At entry, patients completed self-report questionnaires on AIDS-related knowledge and sexual and drug use practices. There was a high rate of understanding of risk associated with drug use and perinatal transmission of HIV. Knowledge of high-risk sexual behavior varied, and knowledge of the medical consequences of HIV was modest. Engagement in several high-risk behaviors was identified: lack of condom use, intravenous drug use, sharing of needles, sex with an injecting drug user, and exchanging sex for money or drugs. AIDS-related knowledge and engagement in high-risk behaviors were not significantly correlated. Authors discussed implications of these findings for developing effective HIV prevention strategies in this population.