Acute respiratory failure (ARF) in patients over 65 years is common in emergency departments (EDs) and is one of the key symptoms of congestive heart failure (CHF) and respiratory disorders. Searches were conducted in MEDLINE for published studies in the English language between January 1980 and August 2007, using 'acute dyspnea', 'acute respiratory failure (ARF)', 'heart failure', 'pneumonia', 'pulmonary embolism (PE)' keywords and selecting articles concerning patients aged 65 or over. The age-related structural changes of the respiratory system, their consequences in clinical assessment and the pathophysiology of ARF are reviewed. CHF is the most common cause of ARF in the elderly. Inappropriate diagnosis that is frequent and inappropriate treatments in ED are associated with adverse outcomes. B-type natriuretic peptides (BNPs) help to determine an accurate diagnosis of CHF. We should consider non-invasive ventilation (NIV) in elderly patients hospitalised with CHF or acidotic chronic obstructive pulmonary disease (COPD) who do not improve with medical treatment. Further studies on ARF in elderly patients are warranted.