This study examined the psychometric properties of the Minnesota Multiphasic Personality Inventory—2 (MMPI-2) Restructured Clinical Scales (RCSs) in individuals with posttraumatic stress disorder (PTSD) receiving clinical services at Department of Veterans Affairs medical centers. Study 1 included 1,098 men who completed the MMPI-2 and were assessed for a range of psychological disorders via structured clinical interview. Study 2 included 136 women who completed the MMPI-2 and were interviewed with the Clinician Administered Scale for PTSD. The utility of the RCSs was compared with that of the Clinical Scales (CSs) and the Keane PTSD (PK) scale. The RCSs demonstrated good psychometric properties and patterns of associations with other measures of psychopathology that corresponded to current theory regarding the structure of comorbidity. A notable advantage of the RCSs compared with the MMPI-2 CSs was their enhanced construct validity and clinical utility in the assessment of comorbid internalizing and externalizing psychopathology. The PK scale demonstrated incremental validity in the prediction of PTSD beyond that of the RCSs or CSs.