The objectives of this study were to describe changes in asthma and employment after diagnoses of occupational asthma reported to the SWORD project: Questionnaires were sent to 312 physicians for all 1,940 cases of occupational asthma reported from 1989-92; 1,769 (91%) were returned but information was available for only 1,317 (68%). Of patients reported by occupational physicians, 45% had recovered from asthma compared to only 14% of those reported by chest physicians (excluding medicolegal cases), presumably because of differences in severity. Proportions with the same employer were 49% and 48% respectively. Patients exposed for a year or more after diagnosis recovered from asthma less frequently but were more often employed than those exposed for less than a year. Among those whose asthma was attributed to high molecular weight agents, smokers had developed asthma earlier after exposure began than others but had the best prognosis. Asthma developed following a single high exposure in 18 cases (2%), of which 13 were to irritants and five to known sensitizers.