Most of the mapping work in Brassica has taken place during the past 10 years. This activity has been focused mostly on rapeseed B. napus and on all three diploid cultivated species, B. nigra, B. oleracea and B. rapa. More recently, mapping has been expanded to include B. juncea. The maps produced in Brassica crops are based mainly on F2 progenies developed independently by various laboratories, which will require in the future their integration for a more efficient use. The marker maps are being used to locate genes determining traits of economic interest, including quantitative trait loci for utilization in applied genetics and breeding of the numerous Brassica crops. Another important application of the maps, which is quite active at the present time, is on the study of the structure, origin and evolution of the Brassica genomes. The Arabidopsis sequencing genome program puts the Brassica crops in an advantageous position because of the immediate application of this information.