Results of mass data screening for 20 different sites of cancer and 50 suspect occupations with exposure to dust were reported. About 22 combinations of occupation and cancer sites had age adjusted relative risks significantly elevated at the 5 percent probability level. Risk of melanoma was the most widespread; highest risk of melanoma was present in blacksmiths, paper industry workers, excavators, millwrights, and roofers. Risk of stomach carcinoma was high among millwrights, operatives in textile industry, and shoemakers. Colon and rectum cancers, lymphomas, and skin cancers other than melanoma did not show significantly elevated risks. Myeloma, leukemia, and cancer of the larynx, lung and testis showed nonsignificantly elevated risks in some occupations. Pancreas cancer was high among workers in miscellaneous manufacturing industries; nose cancer was high in brickmasons, textile workers, and shoemakers. Cancers of the buccalpharyngeal cavity were high in shoemakers, but absent in other occupations, with the exception of roofers. Esophagus cancer was high in brickmasons and lumber workers. Prostate cancer was high in blacksmiths and dairy farmers. Kidney cancer was high in brickmasons and roofers, and bladder carcinoma was high in dairy farmers. Relative risk estimate under the age adjustment procedure was nonsignificant, but became significant when smoking habits were taken into consideration. A hypothesis for the prevalence of stomach carcinoma among ethnics from Eastern Europe was examined in the clerical workers cohort. No stomach carcinoma was recorded in this ethnic subgroup, which comprised 1.7 percent of the clerical population studied. Elimination of the ethnic factor brought up twice as many significant results. Relative risks greater than two and significant at the 5 percent probability level were obtained for blacksmiths, brickmasons, lumber workers, millwrights, and paper and textile industry workers.