This chapter contains sections titled:

• Introduction

• Historical background

• Definition

• Methods for measuring bronchial responsiveness

• Mechanisms and receptors involved in BHR

• BHR in asthma: relation to airway inflammation and airway remodeling

• Asymptomatic BHR

• BHR and antiasthma drugs

• Specific uses of direct and indirect bronchial challenges

• Conclusions

• References