Although much has been published on the effects of the 1990/1991 Gulf War on the psychological health of veterans, few studies have addressed the pattern and timing of post-war development of psychological disorders. Our study aims to identify the most common psychological disorders that first appeared post-Gulf War, the period of peak prevalence and the sequence of multiple psychological disorders. The temporal progression of psychological disorders in male Australian naval Gulf War veterans with no prior psychological disorders was calculated across each year of the post-Gulf War period. DSM-IV diagnoses were obtained using the Composite International Diagnostic Interview. Psychological disorder rates peaked in the first 2 years (1991–1992) following the Gulf War. Alcohol use disorders were the most likely to appear first. Classification and regression tree analysis found that risk of disorder was exacerbated if veterans had been exposed to a high number of potential psychological stressors during their military service. Lower military rank was associated with increased risk of alcohol disorders, particularly during the first 2 years post-Gulf War. In veterans with two or more disorders, anxiety disorders and alcohol disorders tended to appear before affective disorders. Our study found that psychological disorders occur in sequence following Gulf War deployment. Our findings may help clinicians to anticipate, and better manage, multiple symptomatology. The findings may also assist veteran and defence organisations in planning effective mental health screening, management and prevention policy.