Many species of Lymantria are important forestry pests, including L. dispar which is well known distributed from Asia to North America as an invasive species. Like of most other genera of moths, the systematic of this genus is still in dispute, especially on the monophyly and the relationship within this genus due to the fact that genus is very large and varied. This genus was morphologically defined only by a single aphomorphy. To clarify the monophyly of the genus Lymantria, to reveal the phylogenetic relationship among the Indonesian species, and to establish the genetic characters of Indonesian Lymantria, we analyzed 9 species of Indonesian Lymantria involving 33 other species distributed around the world based on nucleotide sequence variation across a 516-bp region in the CO I gene. The results showed that the base composition of this region was a high A+T biased (C: 0.3333). The results also showed that the monophyly of Lymantria was not supported by bootstrap tests at any tree building methods. Indonesian species was distributed into four different groups but the relationship among them was still in dispute. It indicates that relationships among the basal nodes (groups) proposed here were least valid due to the fact that the number of species may not be enough to represent the real number of species in the nature. Moreover CO I gene sequences alone were not able to resolve their relationships at the basal nodes. More investigations were needed by including more species and other genes that the more conserved.