Nonmelanoma skin cancer is the most prevalent malignant disease among light-skinned individuals in the USA, accounting for approximately 1 million new cases annually. Solar ultraviolet radiation is known to be the major cause of skin cancer. The idea that diet, particularly dietary fat, may play a role in modulating cancer incidence has been based largely upon indirect epidemiologic evidence. However, few studies have found correlations of dietary fat intake with skin cancer incidence. Nevertheless, a large body of evidence with experimental animals and one clinical intervention trial, the latter avoiding the pitfalls of many epidemiologic investigations, clearly demonstrate that the level of dietary fat intake can have a significant influence on the occurrence of skin cancer in individuals at high risk.