Asbestos has been widely used in the refinery and petrochemical sector. Mesothelioma has occurred among maintenance employees, and it was hypothesized that mesothelioma is a marker for exposures which might increase lung cancer risk. A death certificate-based case-control study of mesothelioma and lung cancer from 1980 to 1992 was conducted in an Ontario county with a substantial presence of these industries. Each of the 17 men who died of mesothelioma and 424 with lung cancer were matched with controls who died of other causes. The Job and Industry fields on the death certificates were abstracted. Employment as a maintenance worker in the refinery and petrochemical sector was associated with an increased risk of mesothelioma (odds ratio: 24.5; 90% confidence interval 3.1-102). The risk of lung cancer among petrochemical workers, in comparison with all other workers in the county, was 0.88. In an internal comparison of maintenance employees with other blue-collar workers in the refinery and petrochemical sector, the odds ratio for lung cancer was 1.73 (90% confidence interval 0.83-3.6). This finding is consistent with no difference in risk between maintenance and other employees, but it is also compatible with study power being too low to achieve statistical significance. The hypothesis of increased lung cancer risk could be examined more fully with nested case-control studies in existing cohorts. Meanwhile, it would be prudent to reinforce adherence to asbestos control measures in the refinery and petrochemical sector.