As a follow-up to a recent examination of occupation and pleural mesothelioma in Sweden, we evaluated peritoneal mesothelioma using the Swedish Cancer-Environment Registry. There were 35 microscopically confirmed cases of peritoneal mesothelioma among employed men during the period 1961 to 1979. Almost 40% of cases were in the construction industry, with insulation workers at especially high risk (standardized incidence ratio = 163.9, 4 cases, P less than .001). Other groups such as textile and paper and pulp workers and painters showed nonsignificant increases in risk. These findings are consistent with previous studies in their countries, and demonstrate the usefulness of registry epidemiology in assessing occupational relationships to cancer.