While there is high level of comorbidity of PTSD and substance use disorders (SUDs), little research has focused on the overlapping symptom constellation characteristic of both PTSD and substance use/withdrawal. This report describes two preliminary investigations that address this area. In the first study, the pattern of PTSD symptoms in a sample of women (n = 28) seeking treatment for a SUD and comorbid with PTSD was compared with the symptom pattern of a sample of women (n = 28) with PTSD only. The PTSD + SUD group evidenced significantly more symptoms in the avoidance and arousal symptom clusters than the PTSD-only group. At the individual symptom level, the PTSD + SUD group reported significantly more sleep disturbance than the PTSD-only group. It was also determined that the PTSD + SUD group reported greater traumatic-event exposure than the PTSD-only group. In the second study, PTSD symptoms were compared in a sample of alcohol- dependent and a sample of cocaine-dependent individuals with PTSD. The alcohol- dependent group exhibited significantly more arousal symptoms than the cocaine-dependent group. Implications of the results for the assessment of individuals with comorbid PTSD and SUDs are discussed.