In order to measure the prevalence of chronic respiratory symptoms in the population and to identify subjects for a case-referent study of aetiologic factors, 10,000 persons registered with general practices in south east England were surveyed. Responses to an initial postal questionnaire were validated by telephone interview; clinical interviews and simple spirometry were subsequently carried out on a sample of persons aged 5-54 years, reporting persistent sputum production. Results indicated that the postal questionnaire was an effective and sensitive method of surveying respiratory symptoms in the population. Comparison with earlier surveys suggests that the prevalence of chronic cough and sputum in Great Britain has fallen in males but not in females. Of those adults reporting persistent sputum production, high proportions reported associated symptoms of wheezing (54%), breathlessness (45%) or upper respiratory tract symptoms (54%). Thirty percent recalled a serious respiratory infection in childhood and 52% were current cigarette smokers although 34% reported that they had never been regular smokers. Overall there was little evidence of serious airflow obstruction in this group.