Background: Suicidal behavior is one the most significant mental health problems in the military. Militaries are closed systems that operate in particular situations. Military service is associated with certain stressful conditions. On this basis, there is likely of trauma in the military environment. Measures of suicidal behavior are pathologically complex. A range of biological, psychological, social, and institutional factors are involved in the incidence and prevalence of these behaviors.Objectives: One of the underlying factors in suicidal behavior is individuals' personality.Patients and Methods: The study population comprised of the Iranian Armed Forces. To recruit the sample of the research, 1659 soldiers were selected by multistage sampling. Data were collected using the Beck Scale for Suicide Ideation (BSSI) and NEO-Five Factor Inventory.Results: There was a significant positive correlation (r=0.323) between neuroticism and suicide ideation, however, significant negative correlations existed between three other personality traits --extraversion [r=-0.306], agreeableness [r=-0.227], and conscientiousness [r=-0.271] and suicidal ideation. Unlike neuroticism, extraversion and conscientiousness personality factors could reduce significantly (as much 14% as are predicted) levels of suicidal ideation.Conclusions: Based on these results, neuroticism might increase suicide, but extraversion and conscientiousness personality traits are associated with a reduced risk of suicide.