Occupational asthma is the most common occupational lung disease in the world. Occupational asthma comprises approximately 25-50% of occupational lung diseases and is responsible for up to 15% of all asthma cases. Either immunologic or nonimmunologic causes may be responsible for occupational asthma. There are approximately 250 compounds known to cause occupational asthma. Common examples include flour, animal dander, isocyanates, and latex. The diagnosis of occupational asthma depends on an accurate history of asthma and documentation that the asthma is caused by workplace exposure. Peak flow measurements are commonly used to provide data to define this relationship. Spirometry and bronchial provocation testing are also helpful. The key management tool in occupational asthma is avoidance of the causative agent. Avoidance is more important than treatment with medications. Occupational asthma can have major socioeconomic impacts on an individual, and the diagnostic work-up and management needs to be performed with this in mind.