Previous research has shown that patients are not able to learn to use self-administered inhaler devices if they have impaired general cognition, executive (frontal lobe) dysfunction or dyspraxia. These impairments are most frequently encountered in frail elderly people. Some of the tests required to detect such impairments are time-consuming and are therefore not easily adopted in routine clinical practice, particularly in an outpatient setting. We performed a study of 50 elderly inhaler-naïve patients to explore the use of a simple quick drawing test (copying overlapping pentagons) to determine whether that test was able to identify patients who were unable to learn to use a Turbohaler. Patients who were not able to perform the pentagon copying test were found to be unable to learn to use a Turbohaler with a specificity of 93% and positive predictive value of 87%. This was at least as discriminating as the Abbreviated Mental Test and the Mini Mental State Examination. The overlapping pentagon drawing test is useful in clinical practice to identify patients who will probably not use a self-administered inhaler correctly, and who will require an alternative approach to the treatment of their airways disease. This finding might have implications for other self-administered treatment, such as insulin pens and complex drug regimens.