Recent speculation concerning the relationship of dietary fat and cancer causation is challenged. Correlations between increase in per capita dietary fat intake and cancer mortality over a 60-year period show significant positive correlations for total fat and vegetable fat, and negative or no correlation for animal fat. The significant positive correlation for vegetable fat could not always be explained by the effects of total unsaturated components; individual unsaturated components, such as oleic or linoleic fatty acids; or the saturated component; but could be explained by the trans fatty acid component.