Beta-2-Adrenergic receptors (beta(2)AR) participate in the physiologic responses of the lung, including bronchodilation and bronchoprotection, through mechanisms such as mucociliary clearance, fluid accumulation and mediator release from mast cells and basophils. Thus, these receptors may also play an important role in the pathophysiology of asthma. The gene encoding beta(2)AR (ADRB2) is extremely polymorphic, and studies of this gene improves our understanding of asthma and possibly lead to new methods to prevent, diagnose and treat it. This review summarizes results from various studies on the possible relationship of ADRB2 polymorphisms to asthma and asthma-related phenotypes, including bronchodilator responses to inhaled beta(2)-agonists. At present, it appears that, for asthma, ADRB2 polymorphisms are not aetiologically involved. However, they might affect disease severity and clinical response to both acute and chronic administration of beta(2)-agonists. The development is that by assessing the ADRB2 genotype, it might be possible to predict the clinical course of asthma as well as responsiveness to chronic administration of beta(2)-agonists. Carefully, performed and adequately powered clinical trials continue to be important for achieving those goals.