Cancer is the major cause of death in the UK, and the Government has set a target to reduce death rate from cancer in individuals 75 years by ≥20% by 2010. Whilst earlier diagnosis and more effective treatments will contribute to meeting this target, there are considerable opportunities to prevent cancer by improving diet and other aspects of lifestyle. There is now a good understanding of the biological basis of carcinogenesis, which is providing the basis for mechanistic investigation of the chemo-preventive properties of certain foods and food components. It is becoming increasingly clear that there are important interactions between an individual's genotype (characterised by single nucleotide polymorphisms in particular genes) and habitual diet that modulate the risk of developing cancer. The technology to support this post-genomic revolution in nutrition research is now widely available, but brings with it considerable challenges in terms of study design and ethics. However, in the absence of a robust body of evidence on which dietary strategies will benefit which individuals, soundly based genetically-targeted nutrition advice to the public on cancer prevention is a little way in the future.