The butterflies of the genus Parnassius are among the most popular swallowtail butterfly groups of the family Papilionidae. On the basis of morphological comparisons, it has been suggested that Parnassius had undergone much speciation in the Tibetan region since early Tertiary period. Due to the complete lack of genetic information, however, the biological relationships among species and species-groups, as well as the evolutionary scenario of the Parnassian butterflies have thus far only been speculative. In order to shed light on the origins and evolutionary history of this butterfly group, phylogenetic relationships among species of the genus Parnassius and its related taxa were examined by comparing nucleotide sequences of mitochondrial DNA. In the phylogenetic trees, Parnassius was found to be most closely related to Hypermnestra helios, whereas Archon apollinus, which has been classified into the tribe Parnassiini together with Parnassius and Hypermnestra, was more closely related to members of the tribe Zerynthiini. Within the Parnassius clade, six major clades corresponding to species groups were well supportped. However, the branching order of these clades was uncertain and they appeared to be connected to each other by relatively short internal branches. This result suggests that they would have radiated within a relatively short time during a specific period.