Approximately 800 United States Air Force basic military trainees (BMTs) are diagnosed with asthma, annually, resulting in separation from the military. With training costs of approximately 10,000 dollars/person, around 8 million dollarsis lost per year. Improved methods in diagnosing asthma would be beneficial. The aim of this study was to determine the fraction of exhaled nitric oxide (FENO), a marker of airway inflammation, in a military recruit population referred for an asthma evaluation. In BMTs referred for respiratory complaints during basic training, FENO levels were determined before an asthma evaluation consisting of a history, physical, baseline spirometry, and histamine bronchoprovocation. Of 172 BMTs who had symptoms suggestive of asthma and underwent histamine bronchoprovocation, 80% were diagnosed with asthma. FENO levels were significantly higher in asthmatic patients than nonasthmatic patients (mean, 30 parts per billion [ppb] versus 19 ppb, p < 0.001; median, 21 ppb versus 17 ppb, p < 0.02). Various FENO cutoff points provided a range of sensitivity and specificity for the diagnosis of asthma. However, an optimal FENO cutoff level for asthma was not obtained. An FENO value of 10.5 ppb provided a sensitivity of 86% for the diagnosis of asthma, but specificity was only 21%. In contrast, an FENO value of 46 ppb provided 100% specificity but only 17% sensitivity. FENO levels were significantly elevated in BMTs diagnosed with asthma but the lack of an optimal cutoff level limits the test as a diagnostic tool for asthma. Additional studies are necessary to determine the value of FENO for asthma screening in a military population.