Background The United States military has lost more troops to suicide than to combat for the second year in a row and better understanding combat-related risk factors for suicide is critical. We examined the association of killing and suicide among war veterans after accounting for PTSD, depression, and substance use disorders. Methods We utilized a cross-sectional, retrospective, nationally representative sample of Vietnam veterans from the National Vietnam Veterans Readjustment Study (NVVRS). In order to perform a more in depth analysis, we utilized a subsample of these data, the NVVRS Clinical Interview Sample (CIS), which is representative of 1.3 million veterans who were eligible for the clinical interview by virtue of living in proximity to an interview site, located within 28 standard metropolitan regions throughout the United States. Results Veterans who had higher killing experiences had twice the odds of suicidal ideation, compared to those with lower or no killing experiences (OR = 1.99, 95% CI = 1.07-3.67), even after adjusting for demographic variables, PTSD, depression, substance use disorders, and adjusted combat exposure. PTSD (OR = 3.42, 95% CI = 1.09-10.73), depression (OR = 11.49, 95% CI = 2.12-62.38), and substance use disorders (OR = 3.98, 95% CI = 1.01-15.60) were each associated with higher odds of suicidal ideation. Endorsement of suicide attempts was most strongly associated with PTSD (OR = 5.52, 95% CI = 1.21-25.29). Conclusions Killing experiences are not routinely examined when assessing suicide risk. Our findings have important implications for conducting suicide risk assessments in veterans of war. Depression and Anxiety 00:1-6, 2012. © 2012 Wiley Periodicals, Inc. © 2012 Wiley Periodicals, Inc.