The morbidity and mortality from asthma remains high in patients over the age of 75 years in developed countries, in contrast to the improving mortality from that condition in children and younger adults. One of the reasons for this might be the relatively poor performance with inhaler devices confirmed by surveys of technique in elderly patients. This review explores the pattern of observed and measured errors in the use of various inhalers in old age. The physical barriers to a successful grasp of inhaler technique are explained. The review then proceeds to describe a systematic research sequence by the author and others to identify factors that determine the likelihood of an aged person being able reliably to self-administer medication by the inhaled route. Relatively simple tests of cognition, praxis and executive function are described which have been shown to have predictive value in assessing frail elderly subjects for potential inhaler therapy. The evidence presented can enable clinicians to approach inhaled therapy for asthma and chronic obstructive pulmonary disease in a logical and effective way for their frail elderly patients.