Veterans with posttraumatic stress disorder (PTSD) often experience high levels of hostility. Although studies have found that PTSD is associated with poorer quality of life (QoL), increased functional impairment, lower levels of social support, and increased suicidal ideation, it is unclear if hostility impacts these domains in veterans with PTSD above and beyond the impact from PTSD and depressive symptoms. The present study aimed to examine whether hostility is related to several indices of poorer QoL and functioning after controlling for demographic characteristics, PTSD symptoms, and depressive symptoms. Participants (N = 641) were male U.S. veterans seeking PTSD treatment through a specialty clinic in the Veterans Affairs Healthcare System. Veterans completed the Davidson Trauma Scale for DSM-IV (DTS), Personality Assessment Inventory (PAI), Quality of Life Inventory, and the Sheehan Disability Scale. Hierarchical regressions were conducted to examine the impact of PAI measures of hostility on QoL, functioning, social support, and suicidal ideation beyond DTS, depression, race, and age. After covarying for DTS total score, depression symptoms, age, and race, higher levels of hostility were significantly associated with higher degrees of functional impairment and lower degrees of social support, ΔR2 = .01 and ΔR2 = .02, respectively. Higher levels of hostility were significantly related to diminished functioning and lower social support beyond PTSD and depressive symptoms in veterans seeking treatment for PTSD. These findings highlight the importance of assessing and treating hostility in veterans with PTSD.