This pilot study examined: the prevalence of childhood trauma in a sample of male veteran substance abuse inpatients, and the relationship of childhood trauma to substance abuse in this sample, controlling for posttraumatic stress disorder (PTSD). Forty-six subjects were interviewed using the Traumatic Antecedents Questionnaire, Structured Clinical Interview for DSM-III-R (SCID)-P Psychoactive Substance Use Disorders module, the Addiction Severity Index, and the SCID-NP-V PTSD module. Seventy-seven percent of subjects had been exposed to severe childhood trauma. Fifty-eight percent had lifetime PTSD. The total number of lifetime substance dependence disorders was strongly positively associated with total childhood trauma exposure. This relationship remained significant after controlling for demographics, family history of alcohol problems, combat exposure, and lifetime PTSD, including combat-related PTSD. A substantial number of these subjects reported exposure to childhood trauma, which in turn was related to multiple substance dependence. This has important implications for the natural history and prevention of multiple substance dependence disorders.