ABSTRACT An investigation was carried out to determine the cause of death and the incidence of tumours among 1932 workers in a ferrochromium plant in Sweden. The workers had been exposed mainly to metallic and trivalent chromium (Cr3+); hexavalent chromium (Cr6+) was also present in certain working operations. The population was defined as all men employed at the plant for at least one year during 1930-75, and were classified according to their occupation within the industry. The causes of death were initially obtained from parish registers. For deaths occuring between 1951 and 1975, death certificates were collected from the National Central Bureau of Statistics. Data on the incidence of cancer during 1958-75 were obtained from the Swedish National Cancer Registry. Expected death rates and incidence of tumours were calculated, based on the rates for the county in which the factory was situated. The total number of deaths from tumours was less than expected (69 versus 76·7). Five cases of respiratory cancer were found, against an expected 7·2. Among maintenance workers, an increased death rate from all tumours and an increased number of respiratory tumours were found. Two of the latter were mesotheliomas and could be connected with asbestos exposure. No increase was found for respiratory tumours among the heavily exposed workers at the arc-furnaces; one case of mesothelioma was found in this group.