The Swedish Cancer Environment Registry, a population-based Cancer Registry, has been supplemented with 1960 census data on occupation and industry. This information system was used to generate hypotheses on occupational high-cancer-risk groups and to discuss some methodological problems connected with register epidemiology. By successive exclusion of parts of the original population of printing industry workers with excess risks of lung and cervical cancer it was possible to consider similarities and differences between subgroups. Risk estimates from three different standardization methods agreed well for populations with more than 50 cases. Regional adjustment helped arrive at interpretable risk estimates. The excess risk of cervical cancer disappeared when gainfully employed persons and blue-collar workers were used for reference. After the exclusion procedure there was an excess risk of lung cancer among typographers and lithographers in printing enterprises, especially in some birth-cohorts, due possibly to working exposure environment.