Mycorrhizal fungi of the genusTuberare classified by morphological characters that allow differentiation of most species. However, some economically important species are difficult to differentiate on morphological grounds. When morphological traits are not sufficient to discriminate between taxa, other markers are needed. Genetic variation of fruit bodies of 12Tubertaxa was studied by the random amplified polymorphic DNA (RAPD) technique. High interspecific variability was observed between most species. Moreover, important infraspecific variation occurred in all species, exceptTuber brumales.L,Tuber melanosporum, andTuber magnatum. Southern hybridization patterns of RAPD products of the various species were used to confirm the data. Relationships amongTuberspecies were determined by cluster analyses. UPGMA analyses revealed several main clusters and a low genetic similarity between taxa. These results indicate that RAPD and polymerase chain reaction are useful for analysing genetic variation withinTuberspecies. Most species can be identified by differences in their amplified DNA profiles. However, the two pairs of closely related taxaTuber aestivum–Tuber uncinatumandTuber brumalevar.brumale–Tuber brumalevar.moschatumdid not appear to differ genotypically.Key words:Tuber, RAPD, Southern, UPGMA, inter- and infra-specific variability.