In this report the authors discuss public health surveillance in general, NIOSH's Sentinel Event Notification System for Occupational Risks (SENSOR) model, occupational asthma as a target condition for SENSOR, and the implementation of SENSOR and the early experience in selected states conducting occupational asthma surveillance using this model. The SENSOR system consists of four components: a set of selected target conditions, a network of sentinel health care providers, a surveillance to receive and analyze data, and an intervention activity that is guided by the surveillance data. SENSOR targets those sentinel health events (occupational) (SHE(O)) most suited to provider reporting and intervention. A SHE(O) is a preventable work related disease, death, or disability the serves as a signal that other workers in the same workplace, industry, or occupation may be at risk of a similar outcome and may benefit from intervention. Occupational asthma is a SHE(O) because the prevalence of asthma can be high in industries where occupational asthma has been identified. SENSOR programs have been instituted in 10 states, with six identifying occupational asthma as a target condition. Early experience indicates that SENSOR shows promise as an approach to providing occupational asthma surveillance and identifying opportunities for primary and secondary prevention. The implementation and early experience of SENSOR projects on occupational asthma in New Jersey, Michigan, and Colorado were reviewed.