A voluntary scheme for the surveillance of work related and occupational respiratory disease (SWORD) was established in January 1989 with help from the British Thoracic Society and the Society of Occupational Medicine and support from the Health and Safety Executive. Three hundred and fifty four chest physicians representing 90% of the chest clinics in the United Kingdom and 361 occupational physicians submit reports regularly of newly diagnosed cases of work related respiratory illness with information on age, sex, residence, occupation, and suspected causal agent. In 1989 2101 cases were notified, of which frequent diagnoses were asthma (26%), mesothelioma (16%), pneumoconiosis (15%), benign pleural disease (11%), and allergic alveolitis (6%). Incidence rates calculated against denominators from the Labour Force Survey showed very large differences between occupational groups, especially for asthma and asbestos related diseases. Substantial regional variation in the incidence of asthma was not explained by the geographical distribution of high risk industries and was probably due to differing levels of ascertainment. The results imply that the true frequency of acute occupational respiratory disease in the United Kingdom may have been three times greater than that reported.