This report describes two patients who had developed asthma after working as automobile painters with isocyanate-based aerosol paint for two years or over. In both patients asthma was confirmed using the standard diagnostic procedure. One of the subjects was atopic. One was ex-smoker and the other had never smoked. Neither had a family history of asthma. The symptoms occurred after workplace exposure lasting two years in one patient and three in the other. As both reported work-relatedness of the symptoms, they underwent serial peak expiratory flow rate (PEFR) measurement and bronchoprovocation testing. Significant work-related changes in PEFR diurnal variations and in non-specific bronchial hyperresponsiveness (NSBH) were observed in one patient, suggesting allergic occupational asthma (OA), while the other patient was diagnosed work-exacerbated asthma (WEA). Our data confirm that spray painting is an occupation with increased risk of respiratory impairment and asthma.