Background: Asthma morbidity has increased, posing a public health burden. Work-related asthma (WRA) accounts for a significant proportion of adult asthma that causes serious personal and economic consequences. Methods: Cases were identified using physician reports and hospital discharge data, as part of four state-based surveillance systems. We used structured interviews to confirm cases and identify occupations and exposures associated with WRA. Results: Health care workers (HCWs) accounted for 16% (n = 305) of the 1,879 confirmed WRA cases, but only 8% of the states' workforce. Cases primarily were employed in hospitals and were nurses. The most commonly reported exposures were cleaning products, latex, and poor air quality. Conclusions: Health care workers are at risk for work-related asthma. Health care providers need to recognize this risk of WRA, as early diagnosis will decrease the morbidity associated with WRA. Careful product purchasing and facility maintenance by health care institutions will decrease the risk.