Abstract: Phylogenetic analyses of 32 species of Polygonum L. and related genera were conducted on the basis of nrDNA ITS sequences using maximum parsimony. Results suggested that Polygonum did not constitute a monophyletic group,and that one monophyletic clade of Fagopyrum and Parapteropyrum named tribe Fagopyreae was placed outside the two major clades corresponding to tribes Persicarieae and Polygoneae. Furthermore,Koenigia and sect. Aconogonon composed a monophyletic group with a close relationship to sect. Bistorta.