Investigations on breath analysis have provided preliminary data on its potential in the noninvasive diagnosis of lung diseases. Although the conventional comparisons of exhaled breath in study populations (ie, diseased vs healthy) may help to identify patients with various lung diseases, we believe that the analysis of exhaled breath holds promise beyond this scenario. On the basis of preliminary findings, we hypothesize that breath analysis (1) could be applied not only to identify patients with lung disease but also to better phenotype healthy subjects at risk and patients with a particular disease, which is in-line with current efforts toward individualized medicine; (2) could be useful in estimating internal body time to determine the optimal time of drug administration, thereby maximizing drug activity and reducing toxicity (chronopharmacology); and (3) could be applied to monitor drugs or drug metabolites, thus, enhancing adherence to prescribed medications and enabling studies on pharmacokinetics.