The predisposition of experimental animals receiving high levels of dietary fat to certain types of chemical-induced cancers seems well established. However, the measure of response evoked by different types of fats appears to be related to factors other than degree of saturation. Likewise the role of dietary cholesterol in UV-carcinogenesis seems clouded by variations in diet not properly controlled in earlier studies. Whereas the involvement of dietary cholesterol in actinic skin cancer was suggested over 40 years ago, recent evidence lends new concern for the involvement of this natural sterol in UV-carcinogenesis. It is proposed, therefore, to (1) evaluate the effect of nutritional stress factors, i.e., high cholesterol and quantitative and qualitative alterations in dietary fat, upon the incidence of UV-induced skin cancer and (2) to determine whether dietary antioxidants have a moderating effect upon potential predisposition to carcinogenesis by dietary lipids.