A questionnaire developed by the International Union against Tuberculosis and Lung Disease (IUATLD) to assess bronchial symptoms has been tested for its ability to predict the bronchial response to histamine in adults aged 18-64 years living in two areas of southern England. A number of questions were found to be independently associated with increased reactivity in the first randomly selected half of the subjects. These symptoms included wheeze, waking at night with shortness of breath, tightness in the chest or shortness of breath when exposed to animals, dust or feathers and the non-specific symptom of persistent problems with breathing. A predictive score based on these symptoms was more sensitive and only slightly less specific than the question on wheeze alone in predicting the response to histamine in the second half of the subjects. Questions about asthma though more specific were considerably less sensitive than either. Symptoms did not differentiate between reactivity associated with positive skin tests and that associated with smoking.