Sugarcane smut, caused by Ustilago scitaminea Syd., is present in all sugarcane growing areas with the exception o f Papua New Guinea, Fiji and the eastern side of Australia. Breeding for smut resistance is efficient because this trait is fairly heritable but it requires complicated screenings. Moreover, the genetic control o f smut resistance is still unknown. With the objective to identify the mendelian factors involved in sugarcane resistance to smut, two strategies have been implemented (1) QTL mapping in a bi-parental progeny derived from a cross between a resistant cultivar 'R 570' and a highly susceptible clone 'MQ 76/53', evaluated in Reunion island for resistance to smut (2) Association study in a population of cultivars, evaluated in Burkina Faso for resistance to smut. First, the worldwide genetic structure of U. scitaminea was investigated. A total of 142 singleteliospore isolates from 15 countries worldwide were analysed using 17 polymorphic microsatellite loci. All isolates but one were homozygous for all loci, indicating that selfing is the highly preferential reproductive mode of U. scitaminea. In America and Africa, genetic diversity was found to be extremely low and all isolates belonged to a single inbred lineage. This inbred lineage was also found in some parts of the Asian continent where most U. scitaminea genetic diversity was detected. These observations support the hypothesis that the fungus originated in Asia. Thus, the bi-parental population and the population of cultivars used to study the genetic determinism of smut resistance have been evaluated towards isolates from the worldwide lineage. The genetic maps of the two parents o f the bi-parental progeny, 'R 570' and 'MQ 76/53', were constructed using a population o f 198 progeny. A total o f 1666 polymorphic markers were produced using 37 AFLP primer pairs combinations, 46 SSRs and 9 RFLP probes. Linkage analysis allowed the construction of 86 cosegregation groups for 'R 570' and 105 cos