This is a Phase 3 study to determine the sensitivity and specificity of the Aridol bronchial challenge test to detect bronchial hyperresponsiveness in patients with suspected asthma. Patients with suspected asthma of either gender, aged between 6 and 50 years, with only mildly impaired lung function (FEV1 >70%) are to be tested with three different bronchial hyperresponsiveness challenges (Aridol, exercise and methacholine), and the results compared. A clinical diagnosis will also be made at the end of the study.