There is a high prevalence of traumatic events within individuals diagnosed with schizophrenia and of auditory hallucinations within individuals diagnosed with posttraumatic stress disorder (PTSD). However, the relationship among the symptoms associated with these disorders remains poorly understood. We conducted a multidimensional assessment of auditory hallucinations within a sample diagnosed with schizophrenia and substance abuse, both with and without comorbid PTSD. The results suggest a rate of comorbid PTSD similar to those reported in other studies. Patients who have comorbid PTSD reported more distressing auditory hallucinations. However, the hallucinations were not more frequent or of longer duration. The need for a multidimensional assessment is supported. The results are discussed within current theoretical accounts of traumatic psychosis.