The physician's ability to recognize airflow limitation was assessed in 92 stable asthmatics between seven and 12 years of age. A parental symptom score was obtained. The physician assigned a physical sign score and a clinical impression score based on the severity and lability of symptoms. Airflow limitation was considered significant if the forced expiratory flow between 25 and 75% of the vital capacity (FEF25-75) was less than 50% predicted. The FEF25-75 did not correlate with any of the scores and was less than 50% predicted in 27 of 92. There was no clinical suspicion of abnormality in 12 of 27. The FEF25-75 increased significantly after salbutamol inhalation in 22 of 23 but was persistently abnormal on follow-up in 9 of 21. We conclude that without pulmonary function tests the physician may fail to identify significant reversible airflow limitation in 13% of stable asthmatic children.