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.