This study examines the association of traumatic exposure, PTSD and substance use among 1098 out-of-treatment African American drug users. Over 40% of the respondents experienced a DSM-III-R qualifying traumatic event with 44% of those developing PTSD. Early onsets of marijuana and heroin use, alcohol dependence and opiate dependence were each associated with exposure to a traumatic event for males and early onset alcohol use and alcohol dependence were associated with females' exposure to a traumatic event. Alcohol dependence and depression disorder were co morbid with PTSD in men, while the early onset of alcohol and alcohol dependence were associated with PTSD in women. In the 16% of the sample who reported trauma exposure and poly-substance use, the trauma occurred after the onset of all substance use, with the exception of crack cocaine use. Implications for multifaceted treatment which addresses multiple psychopathologies, PTSD, and risk for exposure are discussed.