This study examined the relationship between substance use, trauma history, post-traumatic stress disorder (PTSD), and psychiatric comorbidity in a treatment seeking sample of cocaine dependent individuals (N = 91). Structured clinical interviews revealed that 42.9% of the sample met DSM-III-R criteria for lifetime PTSD. Comparisons between individuals with and without lifetime PTSD revealed that individuals with PTSD had significantly higher rates of exposure to traumatic events, earlier age of first assault, more severe symptomatology, and higher rates of Axis I and Axis II diagnoses. The results illustrate a high incidence of PTSD among cocaine dependent individuals. Routine assessment of trauma history and PTSD may assist in the identification of a subgroup of cocaine users in need of special prevention and treatment efforts.