Previous research has found high rates of psychiatric disorders among veterans with war zone-related posttraumatic stress disorder (PTSD). However, many studies in this area are methodologically limited in ways that preclude unambiguous interpretation of their results. The purpose of this study was to address some of these limitations to clarify the relationship between war zone-related PTSD and other disorders. Participants were 311 male Vietnam theater veterans assessed at the National Center for PTSD at the Boston Veterans Affairs Medical Center. The Clinician-Administered PTSD Scale and the Structured Clinical Interview for DSM-III-R were used to derive current and lifetime diagnoses of PTSD, other axis I disorders (mood, anxiety, substance use, psychotic, and somatoform disorders), and two axis II disorders (borderline and antisocial personality disorders only). Participants also completed several self-report measures of PTSD and general psychopathology. Relative to veterans without PTSD, veterans with PTSD had significantly higher rates of current major depression, bipolar disorder, panic disorder, and social phobia, as well as significantly higher rates of lifetime major depression, panic disorder, social phobia, and obsessive-compulsive disorder. In addition, veterans with PTSD scored significantly higher on all self-report measures of PTSD and general psychopathology. These results provide further evidence that PTSD is associated with high rates of additional psychiatric disorders, particularly mood disorders and other anxiety disorders. The implications of these findings and suggestions about the direction of future research in this area are discussed.