OBJECTIVES: Asthma is a disease associated with inflammation, airway hyperresponsiveness (AHR) and airflow limitation. Clinical diagnosis and management of asthma often relies on assessment of lung function and symptom control, but these factors do not always correlate well with underlying inflammation. Bronchial challenge tests (BCTs) assess AHR, and can be used to assist in the diagnosis and management of asthma. DATA SOURCE: Data presented at the symposium 'Use of inhaled mannitol for assessing airways disease' organised by the Allied Respiratory Professionals Assembly (9) of the European Respiratory Society (ERS) at the ERS Congress, Berlin 2008. RESULTS: Indirect challenge tests such as exercise testing, hypertonic saline or adenosine 5'-monophosphate (AMP) are more specific though less sensitive than direct challenge tests (such as methacholine) for identifying patients with active asthma. Indirect BCTs may be used to diagnose exercise-induced bronchoconstriction or AHR consistent with active asthma, to evaluate AHR that will respond to treatment with anti-inflammatory drugs and to determine the effectiveness and optimal dosing of such therapy. An ideal indirect challenge test should be standardised and reproducible, and the test result should correlate with the degree of airway inflammation. The mannitol BCT provides a standardised and rapid point-of-need test to identify currently active asthma, and is clinically useful in the identification of patients with asthma who are likely to benefit from inhaled corticosteroid therapy. CONCLUSION: In the future, mannitol BCT may be added to lung function and symptom assessment to aid in the everyday management of asthma.