Occupational groups at risk of cancer were investigated by studying the occupation and health history of a hospital population. Occupation was classified by industry and type of work done. Relative risks for the population studied are compared to clerical workers who were chosen as not exposed population. In general, the disease incidence of the clerical workers agree quite well with that of the whole hospital population. Data are given for oral cancer, stomach cancer, pancreas cancer, larynx cancer, breast cancer, uterine cancer, kidney cancer, melanoma, brain cancer, myeloma, esophagus cancer, intestine cancer, nasal cancer, lung cancer, cervix cancer, bladder cancer, ovary cancer, lymphoma, skin cancer and leukemia. Detailed figures for selected cancer sites are given for women operatives in the apparel industry and in the chemical industry.