Dietary guidelines are important tools for educating the general public and helping health professionals promote good health and prevent chronic diet-related diseases. However, it is of major public health relevance that the effect of the guidelines per se is evaluated to make sure that they serve their purpose. The aim of this article is to review the current research on dietary guidelines and their effect on cancer risk and mortality. Since the last 30-40 years, most industrialized countries have had dietary guidelines. The guidelines are based on thorough reviews of the current scientific evidence regarding dietary intake and health. Potential health benefits associated with good adherence to the guidelines have been evaluated in observational studies during the last 15 years, with an increase in the number of studies during the most recent years. Available data on the potential association between dietary guidelines and cancer are limited and inconclusive. A meta-analysis of studies on overall cancer risk shows no protective effect for good adherence to the dietary guidelines as compared with poor adherence. However, good adherence was associated with a 21% reduced risk of colorectal cancer, and 22% reduced cancer-specific mortality.