Abstract
Post-Traumatic Stress Disorder continues to be under-diagnosed among individuals with severe mental illness and substance abuse. In a convenience sample of 64 patients with severe mental disorders being treated at an urban outpatient clinic, 24% met full criteria for PTSD based upon a comprehensive assessment protocol while only 3% were diagnosed with PTSD by clinicians in the medical record (Cochran's Q = 11.267, df 1, p <.001). In contrast, there was a high rate of diagnostic agreement for psychotic and affective illnesses as well as substance abuse. More attention needs to be given to systematically assessing PTSD among severely mentally ill and dually diagnosed individuals because even highly skilled diagnosticians miss the complex presentation of symptoms with which these patients present for treatment.