The objective of this research was to determine whether there are differences in the rate of physician-diagnosed asthma in various occupational groups. A prevalence survey using a population-based administrative database of a sample of the labor force in Manitoba, Canada was used. A sample of 22,561 individuals who were in the labor force at the time of the 1986 census were linked to the provincial administrative health database. The frequency of physician-diagnosed asthma and other obstructive respiratory conditions were measured. A case of asthma was defined as having at least three physician contacts for asthma between April 1, 1986, and March 31, 1990. Data on potential confounding factors such as age, gender, area of residence, income, and education were also available. The results showed that frequency of physician-diagnosed asthma by occupational grouping ranged from a low of 0.1/100 workers to a high of 4.8/100 workers. Three occupational groups, 1) other teaching and related occupations (SOC 279) (OR 2.54, 95% CI 1.18-5.44); 2) fabricating, installing, and repairing occupations of electrical electronic and related equipment (SOC 853) (OR 2.37, 95% CI 1.05-5.33); and 3) other occupations in laboring and other elemental work (SOC 992) (OR 2.51, 95% CI 1.21-5.24) were found to have elevated odds ratios for physician-diagnosed asthma. Datasets linking occupation and health care utilization may be useful tools for surveillance of work-related diseases in general, and for asthma in particular. However, further work should be done utilizing larger databases to determine the overall usefulness of this approach.