Beta-adrenoceptors are members of a large family of hormone and neurotransmitter receptors that initiate their biological function by coupling to GTP-binding regulatory proteins. beta-Adrenoceptors can be subdivided into two main subgroups, designated beta1 and beta2. Atypical beta-adrenoceptors or beta3-adrenoceptors, which are present on adipocytes, have been demonstrated pharmacologically. Their function in adipose tissue is currently being investigated. Beta2-adrenoceptor agonists have played a key role in the treatment of asthma for some 30 years, being used for the relief and prophylaxis of symptoms. There is, however, no evidence that tolerance to the bronchodilator or anti-bronchoconstrictor effects of these drugs is responsible for the deleterious effects reported with the regular use of bronchodilators. In neuropsychiatry, beta-adrenoceptor antagonists have been used for the treatment of acute stress reactions and generalised anxiety, essential tremor and prophylaxis of migraine. In general, they are effective in anxiety disorders if the somatic symptoms are not extreme. For prophylactic treatment of migraine, beta-adrenoceptor antagonists such as propranolol, metoprolol, nadolol and atenolol are the drugs of first choice. In cardiology, beta-adrenoceptor antagonists are an important class for the treatment of high blood pressure, arrhythmias and angina pectoris, and for prevention of myocardial infarction. With chronic treatment, they reduce mortality in hypertension and prolong survival in patients with coronary heart disease.