Abstract: Cordyceps are endoparasitic fungi of insects. The extracts of Cordyceps fruiting body have been found to possess pharmacological effects. Various Cordyceps species are in public forests of Thailand. The aims of this study were to report and characterize morphological characteristics of Cordyceps fruiting body and genetic relationship. Cordyceps samples were collected from public forests of northeastern Thailand. The results of this study showed the information about two new Cordyceps species which were isolated from cicadae and found in a public forest close to Ban Tha-Tum village, Meung district, Maha sarakham province. This study also showed that these Cordyceps fungi developed fruiting bodies on cicada larvae and white mycelium was aggregated and rapidly developed into stromata. Its fruiting bodies were differed from other taxa. The stromata were cyclinderical with the average number of 7-9 per a cicada, 100-160 mm long and 1.5-2.5 mm wide. Phylogenetic analyses of the nuclear large subunit rDNA (Nuc-ls-rDNA) revealed that these Cordyceps specimens MSU002 and MSU003 were genetically closely related to each other (genetic distance value 0.4%) but MSU013 was genetically diverge (genetic distance value 8.8-8.9%) from those samples. It was also found that these Cordyceps species partially shared a genetic background with Cordyceps sinensis, Cordyceps sphecocephala and Cordyceps cassispora. In conclusion, the fruiting bodies of these Cordyceps specimens were extremely unique. The levels of genetic distance and phylogenetic analyses suggested that these Cordyceps were new species.