Some authors have estimated that occupational factors account for between 10% and 20% of adult asthma cases. Among working populations, the prevalence of asthma among artisans and shopkeepers is not well understood in France. A collaboration was established between the Social Security System for the Self-Employed (RSI) and the French Institute for Public Health Surveillance (InVS) to conduct epidemiological surveillance of asthma in this population. A pilot study was conducted with the primary objective of using prescription drug reimbursement data to identify asthmatics and describe prevalence and risk by sector of activity. A sample of RSI members was randomly selected in three regions based on their reimbursement for anti-asthma medications. Predictive models were developed using variables available in the RSI databases (gender, age, reimbursement for anti-asthma medications, type of prescriber), using responses to a standardized questionnaire from a European survey as a reference. The selected model has a sensitivity of 80% and a specificity of 86%. The occupational sectors at highest risk are bakery and pastry making among men, and passenger transportation by taxi or driving schools among women. This model needs to be validated on another population. If the final stages of model development prove successful, it will be possible to conduct epidemiological surveillance of asthma by occupational activity using data from medical-administrative databases without interviewing individuals. (R.A.)