The incidence of, and mortality from, malignant melanoma of skin in whites are strongly influenced by socio-economic conditions. Professional and administrative workers have the highest rates of all. Clerks and salesmen have higher rates than skilled manual workers, who have higher rates than unskilled workers. Women, when classified by the occupation of their husbands, show a similar relationship to social status. The biases of incidence data from systems of cancer registration, and mortality data from death certificates are different, and the consistency of the data from different periods and from different populations suggests that the relationship is real. The bulk of the data is from Britain, but there is sufficient from the U.S. to indicate that the effect is not restricted to one country. No consistent increase in risk was found in outdoor workers compared with indoor workers of similar socio-economic status.