 PTSD is a debilitating disorder that is common among Veterans returning from Iraq and Afghanistan OIFOEF due to the high risk of exposure to combat and other trauma. Recently, emerging evidence suggest a strong link between PTSD and ADHD. The co-occurring ADHD symptoms are likely to reflect the impairment in cognitive function, which often expressed as reduced attention span, concentration difficulties, impaired decision-making abilities, and memory problems LaGarde et al, 2010. Co-occurring ADHD cognitive impairments add another layer of complexity to the disease process and pose more severe impairments in daily function. While treatments for the avoidance, arousal, and re-experiencing symptoms associated with PTSD for military personnel are readily available, substantial gaps exist in the treatment of the cognitive deficits associated with PTSD. Further, ADHD cognitive symptoms are associated with poorer patient attendance to medical appointments, poorer medication compliance and increased risk for psychotherapy resistance and medication abuse or diversion Kolar et al., 2008. Consistent attendance is the best predictor of patient functional recovery from PTSD Tarrier et al., 2000. Subsequently, untreated co-occurring ADHD cognitive symptoms that increase the risk for problems in patients PTSD treatment engagement, PTSD treatment responses, functional impairment, and quality of life have tremendous negative impact on treatment outcome. However, in so far, studies have not examined the impact that treating ADHD cognitive symptoms have on PTSD treatment engagement, outcome, and functional recovery. The proposed study directly addresses this knowledge gap by testing the feasibility and preliminary efficacy of atomoxetine ATX in treatment of ADHD cognitive symptoms among those with comorbid ADHDPTSD. The investigators research is directly responsive to the mission of RRD-SPiRE to maximize functional recovery of cognitive function in PTSD. The outcome of the proposed research will be significant, because it will provide a knowledge base to help determine who is at risk for developing problems with treatment engagement among PTSD patients, thereby allowing for development of early intervention strategies before drop-out. More importantly, the new knowledge may lead to discovering new targets for novel and more effective treatments for PTSD. This novel clinical trial may have immediate benefit to Veterans by enhancing their cognitive function, reducing ADHD symptom related disabilities and further improving quality of life for Veterans with comorbid ADHDPTSD. 