Half the elderly individuals with asthma have not been diagnosed, yet their quality of life is substantially impaired. Primary care physicians should, therefore, be encouraged to ask about respiratory symptoms in elderly patients, and then perform office spirometry for those with symptoms. Airway obstruction increases the likelihood of asthma, but the lack of a 'significant' acute bronchodilator response is clinically meaningless. Methacholine challenge testing is safe and useful for detecting asthma in patients with normal baseline spirometry. Only one in five life-long smokers ever develops chronic obstructive pulmonary disease, so elderly smokers should also be evaluated for reversible airways obstruction. A normal diffusing capacity test will rule out emphysema in current and former smokers. Elderly individuals whose asthma has been diagnosed are often receiving sub-optimal treatment, resulting in poor asthma control and a high death rate. Co-morbidities (recognized or not) are the rule in elderly patients, and these conditions, or the drugs taken to treat them, may exacerbate asthma. Conversely, bronchodilators and corticosteroids used to treat asthma often worsen co-morbid conditions, such as osteoporosis, ocular disease, and cardiac arrhythmias. Therefore, extra caution is needed when treating elderly asthmatic patients, and objective monitoring of their response to each new asthma medication is important.