Antagonists of the beta-adrenergic receptor (β-AR antagonists) are a heterogeneous class of drugs. Selected members of this class are highly recommended in congestive heart failure (HF) and after acute myocardial infarction. Hydrosolubility, half life and prevalent route of excretion define the pharmacokinetic profile of individual drugs, whereas the respective degree of affinity for β1-AR and β2-AR, the level of coexistent agonist properties and several β-AR independent properties (e. g. antioxidant, direct vasodilating effect) contribute to shape the pharmacodynamic profile. Genetically determined differences in the response to β-AR antagonists and, probably, age-related changes in the neuroautonomic system are further source of variability in the effect of β-AR antagonists on bronchial tone. Patients with chronic obstructive pulmonary disease (COPD) are theoretically at risk of worsening respiratory flows and symptoms caused by β-AR antagonists prescribed for concurrent HF or myocardial infarction. Most of these patients, however, do not experience side effects, maybe because the improved haemodynamic due to β-AR antagonists therapy may in turn improve the respiratory function. Occasional patients can develop untoward respiratory effects of β-AR antagonists, and this risk is higher for those with severe COPD or active asthma. We provide some simple common sense rules for selecting patients with COPD or asthma that are suitable for β-AR antagonists therapy while minimizing the risk of adverse respiratory effects.