Little is known about the effects of drugs on small airways. However, the small airways respond to constricting and dilating substances in vitro. Pathologic assessment demonstrates that small airways are inflamed, and the physiology suggests that they narrow and dilate. If after a period of treatment for asthma, all tests including the SBNT are normal, it would be safe to say that the small airways had been treated. However, we need to have some way of imaging the airways to decide whether or not there is abnormality in the small airways and to target the drugs that we are using to treat them. New ways of imaging, measuring, and performing a biopsy of the small airways are needed if we are going to make progress in this area.