An official American Thoracic Society (ATS)/European Respiratory Society (ERS) joint statement was published on July 1, 2009. The Task Force behind this statement was established in 2004. Its work has been based on a narrative literature review, primarily a structured literature search on asthma control, severity and exacerbations between 1998 and 2004. Its goal has been to: “provide recommendations about standardization of outcomes relating to asthma control, severity, and exacerbations in clinical trials and clinical practice, for adults and children aged 6 years and older.” This commentary is intended to summarize the role of biomarkers, and specifically, the Fraction of Exhaled Nitric Oxide in the ATS/ERS statement.