The current technical report presents the results of a research project in two Natura 2000 sites, namely the National Park of Oeta Mountain (GR2440004) and Tymphristos mountain (GR2430001). OITI project concerned the Orthoptera community of the two mountains and specifically their endemic and/or threatened species. It presents the objectives of the study, the methods and protocols used during fieldwork, and the research findings as follows: overview of the threats and pressures recorded in the study area, inventory of the recorded orthoptera fauna in the two protected areas, a thorough ecological overview of target species, presenting their conservation status (distribution, population status, habitat preferences , pressures and threats). The study suggests the inclusion of 11 important orthoptera species in the Standard Data Forms (SDFs) of the Natura 2000 sites, evaluates the ecological importance of the study area in terms of Orthoptera fauna conservation, and provides an evaluation of the pressures/threats that need to be addressed. It concludes to a conservation guideline relevant to (a) providing permissions for projects that cause land use change on target species habitats, such as renewable or tourist infrastructure, (b) livestock grazing management, (c) biomonitoring of target species, (d) Natura 2000 area expansion.