The bat species occupy a specific ecological niche due to their ability for flight, for hibernating and for using as trophic resources insects and other invertebrates with crepuscular and nocturnal life mode. In the Republic of Moldova the bats hibernate about 4-5 months during the cold period of the year. The hibernation roosts can be of natural and antrhopogenic origin. The abandoned stone quarries from Saharna are situated on the right bank of Nistru river and represent a complex of mines connected with tunnels, where several bat species hibernate. The air temperature in summer period varies from +180C and +130C and in cold period from +2,50C to +70C, the humidity reaches up to 80%. The studies were performed at the end of January 2016. At the entrance the air temperature was of +9°C, the humidity – of 44%. At about 20m from the entrance the temperature was +6,3°C, the humidity – of 43%. About 4 km of underground passages were studied. The bat species were identified without removing from the shelters, to not disturb the hibernation process. In the study period 336 individuals from 8 species have been registered: Rhinolophus hipposideros, Barbastella barbastellus, Myotis daubentoni, M. dasycneme, M. mystacinus, M. blythii, Plecotus austriacus and Eptesicus serotinus (fig. 1). The dominant species was E.serotinus with 55.36% and constituted more than half of hibernating community. In the previous years of study the Serotine bat was also dominant and constituted between 40% and 65% of bat community. The pond bat constituted 13.1%, followed by lesser horseshoe bat (9.52%), Barbastelle bat (7.44%), grey long-eared bat (7.15%) and M. blythii with 5.65%. The least numerous were M. dasycneme and M. mystacinus with 0.89% each. During the study the brown long-eared bat wasn’t recorded, while in the past year it constituted 0.47%. P. austriacus was more abundant (7.44%) by comparison to the previous year (2.35%). Figure 1. Structure of bat community in Saharna quarries in winter 2016 The first individuals, belonging to E. serotinus and P. austriacus were observed at 3-5 m from the entrance. The Plecotus species usually hibernate near the entrances of underground shelters, up to 8-10 m, while the serotine bat can be found near the entrances, as well as deeper in the underground. The first individuals of B. barbastellus were found at about 40 m from the entrance, where the air temperature was of +5,5°C and the humidity – of 44%. The first individuals of M. daubentoni were found at about 50m from the entrance, where the air temperature was of +5°C and the humidity – of 45%. The Serotine bat individuals were found in solitarily and small groups, ranging from 2 to 12 individuals. Other species were found exclusively solitarily. It must be mentioned the increase of B. barbastellus species with approximately 5% in comparison with the previous studies. It is a very rare species of our fauna, included in the Red Book of the Republic of Moldova as critically endangered species, and Saharna site represent the only known hibernation place of this species in R. Moldova. Also, in the third edition of the Red Book (2015) are included the species Rh. hipposideros, M. dasycneme as endangered species, and M. daubentoni, M. mystacinus, M. blythii and P. austriacus as vulnerable species. The abandoned stone quarries from Saharna represent an important bat hibernation roost, where hundreds of individuals from about 10 species, including rare and endangered species, spent the winter. The monitoring of this site will continue. The work was performed within the fundamental project 15.187.0211F at the Institute of Zoology of A.S.M.