The metered dose inhaler (MDI) technique of 30 elderly patients (mean age 79.9 years) was assessed. Sixty per cent were competent, though only 10% had an ideal technique; 40% were incompetent. Inadequate timing of actuation and inhalation was the most frequent error made. Competence was significantly related to mental status questionnaire (MSQ) scores of 7/10 or more. Patients who were first prescribed an MDI in hospital were significantly more likely to be competent than those prescribed an MDI by the general practitioner. Competence was not related to age, underlying diagnosis or duration of MDI therapy. Elderly patients requiring MDI therapy should be carefully selected and properly instructed by the prescribing doctor.