Brassica crop species and their allies ( Raphanus, Sinapis, Eruca, etc.) are important sources of edible roots, stems, leaves, buds and inflorescences, as well as of edible or industrial oils, condiments and forage. Many well known names of plants or plant products, such as kale, cabbage, brocolli, cauliflower, Brussels sprouts, kohl-rabi, Chinese cabbage, turnip, rape, rutabaga, swede, colza or rapeseed, canola, mustard, rocket, etc. are directly associated to this botanical group. The scientific interest for this botanical group has run parallel to its economical importance, and research achievements in our days would have certainly appeared unimaginable only two decades ago. As the end of the millenium approaches, entirely new fields (transformation, somatic fusion, etc.) have been added to the classical ones. Thus, nobody can doubt the opportuneness of this book, which combines and presents both the basic and applied biological aspects of the Brassica species.