Bronchial provocation tests are of value in the evaluation of airway hyperresponsiveness. Nonspecific bronchial challenge (methacholine, mannitol, exercise, etc.) is used when the symptoms, physical examination, and measurements of pulmonary function are unremarkable in the diagnosis of asthma, when a patient is suspected of having occupational asthma or exercise-induced bronchoconstriction (EIB), and when a screening test for asthma or EIB is required for some occupational groups in whom bronchospasm would pose an unacceptable hazard. Methacholine inhalation challenge is most widely used pharmacologic challenge and highly sensitive. For appropriate interpretation of the results of methacholine provocation, it is important to perform the test with the standardized protocol and to recognize that inhalation methods significantly influence the sensitivity of the procedure. Indirect challenges (e.g., mannitol and exercise) correlate with airway inflammation and are more specific but less sensitive for asthma. Indirect provocation tests are used to confirm asthma, to differentiate asthma from other airway diseases, and to evaluate EIB. (Allergy Asthma Respir Dis 2018;6:14-25)