A number of cancers, such as cancer of the large bowel, breast and other hormonal dependent organs, are less frequent in Mediterranean countries than in northern Europe. It has been hypothesized that a low dietary intake of saturated fat, accompanied by a higher intake of unrefined carbohydrates, and possibly other protective nutrients could be the cause of such risk differences. Cohort and case control studies based on individual dietary intake, however, cannot definitely corroborate the theory, nor disprove it. Analytical studies on fat, fibre and breast and colon cancers are reviewed and priorities for further studies are discussed.