Recent literature suggests that posttraumatic stress disorder (PTSD) patients are at an increased risk of suicidal behavior. The purpose of our study was to assess the impact of psychiatric comorbidity on suicidality (as assessed by SUAS) and relationship to combat exposure (as assessed by CES) in 277 veterans suffering from chronic PTSD. The diagnosis of PTSD and psychiatric comorbidity was confirmed according to DSM-IV criteria. Patients with PTSD and comorbidity had significantly higher scores (p<0.01) on the measures of suicidality and combat exposure than the groups without psychiatric comorbidity. These findings suggest that persons with PTSD and psychiatric comorbidity are at a higher risk of suicidal behavior. Therefore, on assessing suicide risk in PTSD patients attention should be paid to comorbidity factors, in order to reduce the risk of fatal complications.