While previous research has found strong associations between childhood maltreatment trauma and substance use disorders (SUDs), the role of possible moderating effects of gender and mediating effects of psychopathology and SUD is unclear. The objective of this study was to investigate differences in self-reported childhood maltreatment trauma, general psychological distress, and post-traumatic stress symptoms between 112 patients in treatment for substance use disorders (SUD group) and 112 matched controls with mild to moderate mental health disorders (comparison group). Childhood maltreatment trauma was measured by the Childhood Trauma Questionnaire - Short Form (CTQ-SF). General psychological distress was measured by the Symptom Checklist-90 - Revised (SCL-90-R), and post-traumatic stress symptoms were measured by the Impact of Event Scale - Revised (IES-R). The SUD group reported more severe childhood maltreatment trauma than the comparison group. Females in the SUD group reported more severe and various forms of trauma compared to males. The SUD group reported higher mean scores on the SCL-90-R, but the proportions of people with caseness scores on the IES-R and the SCL-90-R were similar in the two samples. The SUD group reported more avoidance symptoms than the comparison group. This study adds further evidence to the repeatedly found strong associations between childhood maltreatment trauma and SUD, implying that the prevention of childhood maltreatment trauma may reduce the occurrence of SUD. Furthermore, patients with SUD should be screened for childhood maltreatment trauma, and the results should be applied in trauma-informed as well as trauma-focused interventions aimed to help this population. The association appears to be particularly strong for female substance users.