Previous research with substance users has demonstrated, across a variety of psychiatric disorders, significant decreases in psychological symptoms during early substance abstinence. To build on this literature, the current study prospectively assessed trauma symptomatology over 28 days during acute and protracted cocaine and alcohol abstinence. Participants were 162 male and female cocaine and/or alcohol dependent outpatients who reported a history of trauma. Trauma-related symptoms and substance use were assessed at 2, 5, 10, 14, 21, and 28 days following last substance use. For participants who were known to relapse, assessments began again after the last day of substance use. Latent growth modeling was employed to estimate changes in posttraumatic stress disorder (PTSD) symptoms. Consistent with studies of other psychiatric syndromes, PTSD symptoms declined across the 28-day study period regardless of withdrawal substance (i.e., cocaine or alcohol). The majority of change in trauma symptoms occurred within 2 weeks of last substance use. Moreover, while trauma symptoms for the PTSD participants were more severe than those reported by the non-PTSD participants, trauma symptoms declined across the study period at the same rate irrespective of PTSD status.