Cancer is related not only to genetic backgrounds but also, more predominantly, to environmental factors. Plant-based foods, including fruit, have long been considered as providing protection. Epidemiological studies have shown that individuals who consumed the most fruit had a lower risk of cancer. However, data can significantly differ according to whether it comes from individual case studies or cohort studies. The role of fruit in cancer prevention probably results from its chemical content. Besides vitamins and minerals, phytochemicals, including carotenoids and polyphenols, interfere with carcinogenesis pathways. At the initiation, promotion and progression stages of transformed cells, the phytochemicals act as blocking agents or suppressors. Despite the wealth of basic scientific data available, intervention studies with phytochemicals have had disappointing and even deleterious results. The article discusses chemoprevention using the isolated compounds at pharmacological doses.