Part 1 Principal sources of molecular markers, D. de Vienne et al: criteria of classification; codominant markers detected individually; patterns of multiple dominant markers - genetic fingerprinting; polymorphism of number of tandem repeats; gene markers - cDNA and proteins; what markers are suitable for what purpose?. Part 2 Construction of genetic linkages, D. de Vienne: the concept of genetic distance; comparing the most commonly used populations; F2 populations; recombinant inbred lines; populations derived from non-fixed parents; comparing the various types of populations; fundamentals of genetics maps. Part 3 Mapping of major genes, D. de Vienne: approaches to mapping of major genes; use of markers for cloning major genes. Part 4 Mapping and characterizing quantitative trait loci, D. de Vienne and M. Causse: principle of QTL mapping; genetic and molecular bases of quantitative trait variation. Part 5 Molecular markers in population genetics, A. Kremer and S. Mariette: specific contributions of molecular markers in comparison to enzyme markers; analysis of molecular diversity; polymorphism within a population; differentiation between populations; gene flow. Part 6 Application of markers in selection, A. Charcosset and A. Gallais: contribution of diversity studies to selection; marker-assisted selection; marker-assisted recurrent selection; appendices.