Abstract-Mild traumatic brain injury (mTBI) and posttraumatic stress disorder (PTSD) are prevalent dual impairments in veterans returning from the wars in Iraq and Afghanistan. Attention problems are a common self-reported complaint of veterans with mTBI, but relatively few studies have investigated the types and levels of behavioral attentional deficits present in veterans with mTBI and PTSD. The purpose of this study was to compare visual attentional performance between samples of veterans with both mTBI and PTSD (mTBI+PTSD), PTSD only, and a control group. Overall, the attentional responses of the mTBI+PTSD group were slower than those of the PTSD and control groups. The response times were also more variable, suggesting difficulty with attentional vigilance. Additionally, we found evidence of hemispheric asymmetries in attentional performance. Participants with mTBI+PTSD were less efficient in orienting visual attention to stimuli flashed to the left visual field (LVF), suggesting a right hemisphere deficit. Overall, we found that veterans who had sustained an mTBI and had a coexisting PTSD diagnosis displayed longer response times and were less accurate than the PTSD and control groups, especially when cues were presented to the LVF.