Abstract: The ITS regions of 2 closely related species Allium tuberosum Rotuer. ex Spreng. and Alllium ramosum L. in Allium Sect. Rhiziridium G. Don were amplified, cloned and sequenced. The genetic re-lationships among 10 materials of diploid, triploid, tetraploid and aneuploid in Allium tuberosum and All-lium ranwsum were reconstructed based on ITS1 + ITS2 sequences. The results demonstrated that the aver-age Kimura pairwise distance between Allium tuberosum and Allium ramosum was 0.0146. They are a pair of closely related species. Although it was gone through evolution by artificial selection and natural selec-tion, Allium tuberosum kept little differentiation from Allium ramosum. Sequences of ITS region show that there are no evident differentiation among the various diploid, triploid, tetraploid and aneuploid of Allium tuberosum.

Key words: Allium tuberosum