Tomatoes have become a dietary staple for humans in many parts of the world. The characteristic deep red color of the ripe tomato fruit and related products is mainly due to lycopene. Lycopene is the predominant carotenoid in tomatoes, followed by a-carotene, b-carotene, g-carotene, and phytoene, as well as by several other minor carotenoids. Tomatoes and tomato-based foods have long been an important source of lycopene in the Western diet. There has been a growing interest in exploring the role of lycopene in the prevention of a variety of nutritional and health issues in humans, including some cancers and cardiovascular diseases. Recently, many case studies using cell cultures, animal models, and epidemiological investigations have shown a relationship between lycopene intake and a lowered risk of contracting some cancers and various chronic diseases. Increasingly, clinical evidence supports the role of lycopene as a nutrient with important health benefits, since it appears to provide protection against a broad range of epithelial cancers. The possibility that consumption of lycopene-rich foods may reduce the risk of such diseases has prompted numerous in-depth studies of the levels of lycopene in foods and of correlations between dietary lycopene and certain diseases. This monograph will serve as a reference for providing a better understanding of the role of lycopene in promoting health, and by encouraging a deeper understanding of approaches to a healthy diet and life.