Abstract: β₂-Adrenoceptor agonists are highly effective bronchodilators and are widely used in the treatment of both chronic obstructive pulmonary disease (COPD) and asthma. In the last 15 years, there has been great interest within the pharmaceutical industry in the discovery of a long β₂-adrenoceptor agonist for a mono-therapy or combination therapy. The search for new long-acting β₂-adrenoreceptor agonists (LABA's), for the treatment of asthma and COPD, has become a very active area of drug discovery. This article reviews the mechanisms, potential candidates and research advances of long β₂-adrenoceptor agonists.