Purpose of review Over the past twenty years, work-related asthma has been increasingly recognized to focus on three entities; occupational asthma, work-aggravated asthma, and reactive airways disease syndrome. Of these three entities, work-aggravated asthma has been recently identified to be important in worker health, but little is known about its impact on worker health. Recent findings In this review, it is our intent to summarize the different 'types' of work-related asthma and to emphasize what is known about the outcomes of these three types, with emphasis on work-aggravated asthma. Although data is scanty, compared to occupational asthma and reactive airways dysfunction syndrome, it appears that work-aggravated asthma may well have a very important level of impact on worker health that has not been well recognized in the past. Summary All of these entities have the potential to adversely alter the health of workers and, in many instances, require the worker to leave the job. Of these three entities, it appears that most is known about the natural history of occupational asthma. The recognition that workers must leave the workplace when this diagnosis is made is generally agreed upon. The second entity, reactive airways dysfunction syndrome, is not as clearly understood, particularly when one recognizes that there appears to be a considerable difference in the prevalence of this illness when one compares prospective and retrospective reporting of the disease. Finally, work-aggravated asthma remains the least well described and has only been accepted as a part of the triad of work-related asthma in the past several years. The most appropriate clinical response to the diagnosis of this entity in workers has yet to be fully explored.