Preliminary data are reported from a study of 269 cadmium-nickel battery factory workers and 94 cadmium-copper alloy factory workers. The target group comprises all workers with more than 5 years exposure to cadmium at any time since the factories started production. An internal reference group of 328 alloy factory workers without cadmium exposure was also studied. The expected number of deaths and cancers was calculated with the "life-table" method by using national average incidence rates for men in different age groups and at different calendar years. It was found that among the workers in the battery factory who started work before 1948 there was an increased general mortality in the 1950's mainly due to respiratory disease. The same group had an increased renal disease mortality. There was no increase in general cancer mortality or in general cancer incidence. The risk ratio for nasopharyngeal cancer incidence was 10 (two cases), which was statistically significant. For some other sites like prostate, lung and colon-rectum the risk ratios were also greater than 1 but not statistically significant. In the alloy factory there was a tendency for an increased mortality in prostatic cancer (four cases). After correction for the "healthy worker effect" using the reference group, the risk ratio for prostatic cancer deaths was calculated as 2.4, but this was not statistically significant. The findings in this study support the earlier reports of an association between human cadmium exposure and increased risk for prostatic cancer.