The data obtained during our research are very important for the knowledge of geological setting of Slovenia and international, mainly neighboring territories, as well as our natural heritage. Slovenia is situated in a junction area of three large geotectonic units - the Alps, the Dinarides and the Pannonian basin, and therefore represents a key area for their interpretation. The knowledge of composition of surface rocks enables correct interpretation of subsurface geological setting, what is important at tracing of underground water currents, geothermal research, the studies of seismic activity, exploration of mineral and energy resources, and knowledge of geochemical background prerequisite for environmental studies. Besides correlation of geological structures and rock formations with the neighboring states, some environments and geological formations attract international interest, i.e. carbonate rocks at the Permian/Triassic boundary (about 225 Ma ago), and at the Cretaceous/Permian boundary, about 65 Ma ago. The above mentioned geological boundaries are recently intensively studied in the World because of catastrophic events in geological history, but are well developed only at few localities. Particularly interesting is the K/Tc boundary, which can be traced in limestone at Karst (Kras), developed mainly in a deep-water environment. International geological community is particularly attracted by the studies of geological conditions influencing the development of classical karst, publications on Pliocene volcanic activity in northeastern Slovenia (Goričko), and igneous and metamorphic rocks from the Pohorje Mountains. A great part of the study is multidisciplinary, some of the studies were carried out through cooperation with geologists from the neighboring countries. The mentioned studies are good affirmation of Slovenian geologists in aboard.