This study examined sexual and drug use behavior in 247 methadone maintenance patients, to explore the association of cocaine use with human immunodeficiency virus (HIV) risk behavior. In univariate analyses, cocaine use was positively associated with any drug injection, number of injections, and sexual intercourse without condoms. These relationships remained significant after controlling for other drug use and demographic factors. Heroin use also contributed to injection-related risk. We conclude that cocaine use represents a continued source of risk for exposure to HIV in this population, and that more aggressive efforts are warranted to reduce illicit drug use, particularly of heroin and cocaine, in methadone patients.