To further explore the complex relationship between posttraumatic stress disorder (PISD) and substance use disorders, the authors compared 30 women with PTSD in substance abuse treatment with 25 women without PTSD in substance abuse treatment on degree of addiction severity, psychopa-thology, and aftercare compliance. Women with PTSD were more likely to have been victims of sexual and physical abuse, particularly childhood abuse. They had significantly higher scores on the Addiction Severity Index, were more likely to have comorbid affective disorder, and less likely to comply with aftercare. These results suggest that screening for victimization and PTSD among women presenting for substance abuse treatment may have important prognostic and treatment implications.