Epidemiological studies performed during the last 20 years support an inverse relationship between the individual intake of fruits and vegetables and the risk of cancer. In taking into account some recent conflicting data, a working group of the Nacre network, the French Network for Food and Cancer Research, has conduced a critical analysis of epidemiological and experimental studies, including the preliminary data from the Epic cohort, the European Prospective Investigation into Cancer and Nutrition, to clarify the role of fruits and vegetables to prevent cancer. To date, a high intake of fruits and vegetables (at least, 400 g per day) is appropriate to lower the risk of cancer. Fruits and vegetables provide numerous phytochemicals which, in part, may explain their beneficial effect. Thus, studies in animal models and in cell-culture systems have furnished a lot of information about the potential mechanism by which a diet high in fruits and vegetables may reduce the risk of cancer in humans. However, more investigation in the identification of the biologically active constituents, in the knowledge of their availability and the mechanism by which they contribute to lower the risk of cancer, will increase the scientific support of a public health policy.