We have constructed restriction site maps of the 5.8S rRNA gene and two ITS regions in 60 strains of Kluyveromyces genus. We test the value of this region as a phylogenetic indicator, and its possible use as a fast and easy method to identify species of this genus. Despite some minor incongruences, our results are in good agreement with previous phylogenetic reconstructions based on the 18S rRNA gene sequencing (Cai et al., 1996; James et al., 1997). A highly significant monophyletic group was formed by K. lactis, K. marxianus, K. aestuarii, K. dobzhanskii and K. wickerhamii, which should be considered the true Kluyveromyces genus. The other species of the genus were grouped with lower bootstrap levels. Finally, the restriction map showed by three K. lactis strains, previously identified as K. marxianus var. drosophilarum, could be interpreted as indicatory of the possible existence of different species.