The mortality and cancer incidence experience of a 10% sample of the Canadian labour force has been monitored by using computerized record linkage to the Canadian National Mortality and Cancer Incidence Data Bases. Occupation and industry data are available for the sample for the years 1965-1971, and the data are being used both to generate and test hypotheses concerning occupational exposures and increased risk of various cancers. It is planned to continue the monitoring process in future years, and as the number of cancer cases and deaths in the cohort accumulate, the data will provide an increasingly valuable utility for cancer researchers.