The hydrogen- and oxygen isotope composition of precipitation is subject to spatial and temporal variations. The concentration of isotopes in precipitation depends on prevailing meteorological and geographical parameters. Knowledge regarding the content of heavy water isotopologues (especially HDO, HTO und H218O) in precipitation provides the basis for numerous studies in the field of isotope hydrology, climatology and paleoclimatology.This thesis presents the results obtained from monthly precipitation samples collected at the meteorological station Graz-University. In further consequence the isotope signal of this station will be compared to isotope signals of other Austrian stations. In Graz, the analyses of monthly precipitation samples in terms of isotopic composition began in 1973. The station is part of the Austrian Network of Isotopes in Precipitation (ANIP), where data of several stations in Austria are documented. In addition, the station of Graz-University provides meteorological data (e.g. temperature and precipitation amount). For instance, a "Local Meteoric Water Line" could be defined by using these data. Moreover, other correlations of isotopic data with meteorological and geographical data are determined. The results of this thesis can be used in future climatological, paleoclimatological, hydrological and hydrogeological studies.