ABSTRACT— In a Danish cohort of schizophrenics consisting of 6,168 patients followed during 1957–1980, the incidence of certain types of cancer has been shown to be significantly decreased (5). From this cohort 30 males with lung cancer, 21 males with bladder cancer, 17 females with cancer of the uterine cervix and 40 females with breast cancer, were each matched to two “healthy” schizophrenic controls from the same cohort. A range of social, demographic and nosocomial factors were registered from the individual case files, and statistical analysis was carried out, using Cox's regression model. Neuroleptic treatment with various drugs other than reserpine reduced the risk of developing all four cancer types studied. In contrast reserpine treatment increased the risk of developing cancer of the breast and uterine cervix. Furthermore, cancer risk was found to be modified by other well-known risk factors.