Nowhere is it more important to maintain peek mental functioning than in a combat zone. Conditions ranging from pain to head injury to post-traumatic stress disorder can cause impairments in neuropsychological function and place service members at risk. Medications can sometimes help alleviate these problems, but also have the risk of further slowing cognitive function or impairing reaction time. Standard methods of neuropsychological testing are often not available in a combat environment. New technologies are being advanced that can allow portable, computerized neuropsychological testing to be performed at almost any location. We present a case that demonstrates how the use of such handheld technology can assist a military physician in assessing the influence of medication on reaction time and in determining if and when a service member is ready to return to combat.