Objective: Identification of Heracleum species is difficult due to minor differences of their morphologies. The objective of this study was to formulate hypotheses about relationships of Heracleum species within Apioideae using evidence derived from internal transcribed spacer regions of nuclear ribosomal DNA. Internal transcribed spacers may provide a valuable source of interspecific markers in Apiaceae. These regions appear well suited to comparisons among related species and/or closely related genera.,Methods: Dried seeds of seven Heracleum species were collected. Total genomic DNA were isolated from endosperm layer of seeds collected for each species. Double stranded DNAs of the complete ITS regions in each genomic DNA were amplified. ITS4 and ITS5 regions of nuclear ribosomal DNA were sequenced.,Results: Phylogenetic trees were obtained using ITS DNA sequence data of Heracleum species. Sequences were potentially phylogenetically informative. ITS2 included more potentially informative characters than ITS1.,Conclusion: In the Gene Bank, there is limited sequence data for the studied species. These data may help better understand the phylogenetic relationship of some Heracleum species of large and taxonomically complex Apiaceae. These results are especially important for Apioideae, which has served as an important system in many evolutionary studies