Genome mapping studies have been focussed on modern cultivars for a better understanding of their complex genomic structure. This resulted in the construction of a detailed RFLP linkage map and also the investigation of some aspects of chromosome inheritance and pairing behaviour in cultivars. As a complement, DNA in situ hybridization on chromosomes allowed the assessment of the basic chromosome number of ancestral species and of their contribution to the genome of modern cultivars. Comparative mapping with distant diploid relatives revealed a large amount of chromosome structure conservation between species, especially between sugarcane and sorghum, and to a lesser extent between sugarcane, maize and rice. Field experiment on selfed progenies of R570 allowed to identify a major rust resistance gene and several QTL for yield components. These results showed that identification of QTL is possible despite the high ploidy level of cultivated sugarcane clones.