Region of the Adriatic Sea and the Dinaric Alpes is one of the hotspots and the centre of European biodiversity. The Orthopteran fauna of the Western Balkans, depite being among the richest in Europe continent, remains understudied. This thesis investigates grasshoppers’ and crickets’ distribution patterns in the Adriatic and the Dinaric basins and compares the area with the zoogeography of Greece. Literature, field data, museum collections data and online databases containing data on Croatian, Italian and Greek Orthoptera were studied. For each data-set, a binary matrix was coded. Data were analysed and visualized by principal component analysis (PCA) and the heatmap, in the ClustVis online program. Both, the Adriatic and the Greek islands are divided into five groups, some of which really represent biogeographical units, others being artefacts caused by the small number of the species. The Adriatic islands and the Dinaric Alps can be divided into two main regions. The main factor for the diversity is (island or mountain) size. There are overlaps in the biogeographical characters of some areas. The Dinaric Alps are divided into four groups, one continental and three Adriatic, among which there are overlaps. The analysis divided Greek mountains into four groups, among which there are almost no overlappings. The Adriatic area shows its uniqueness and can be clearly separated from the Pannonian area and from other coastal areas, e.g. the Aegean islands. The island of Corfu, located in the Ionian Sea next to the Greek coast, shows more biogeographical similarity to the Adriatic island, than to the Aegean. Large Adriatic islands have more species than small islands. Small islands are hence not suitable for the biogeographic analyses, as this one. They are, to software, difficult to calculate and to group with larger islands due to the limited number of random species.