OBJECTIVE: This systematic review was conducted to assess published literature that estimated the suicide risk of military veterans relative to nonveterans, to identify differences in suicide risk and, if indicated, to identify causes of such differences to orient preventative measures. METHODS: I performed a systematic review of literature regarding suicide risk of U.S. military veterans relative to U.S. nonveterans. Studies were not excluded based on method of suicide. Studies counting suicides were preferred to studies of ideation or attempts. Intervention studies were excluded. RESULTS: Studies that met inclusion criteria were scrutinized in terms of methods, comorbidities, demographics, potential causes, general conclusions, and posited theory. I identified 115 unique studies from PubMed, Scopus, PsycInfo, and CINAHL, and secondary references. Of these, 13 studies offered direct and original comparisons of veteran and non-veteran suicide risk. CONCLUSION: Increased risk of suicide among Vietnam veterans was best demonstrated by Hearst et al. (1986). The cause(s) of that increased risk are unknown but are unlikely unique to the Vietnam era. Suicide risk is not distributed evenly among veterans. Individuals who volunteer for military service are more likely to have had a pre-military trauma, but lower military suicide rates suggest a social structure protective against suicide. Suicide risk peaks in veterans immediately after discharge. The causes of these increases are unknown. Several theories are discussed.