A questionnaire on the pattern of drug taking was completed by 185 patients with chronic airflow obstruction. Of these, 49% admitted to taking their prescribed therapy regularly and 33% could be regarded as being fully compliant. The use of increasing numbers of drugs was not accompanied by a fall in compliance. Regular drug taking was better in patients (particularly females) with asthma than in patients with chronic bronchitis and emphysema. During acute exacerbations of airflow obstruction, excessive use of bronchodilators beyond the recommended increase in medication was rare; indeed, underuse of therapy in this situation was commoner. These conclusions must be regarded as tentative since the questionnaire was not validated by repeat interviewing or measurement of drug usage.