GPS technology has certainly represented a revolution for telemetry. Geographic locations (XY coordinates) of collared animals can be obtained from satellites (via VHF/GSM download or directly via ARGOS system), along with other data, such as activity, outside temperature and precision of the localisation. However, the potentially huge data sets collected by GPS collars may represent a challenge, both in terms of data management and spatial analysis. 25 roe deer (16 females and 9 males) have been captured and marked with GSM-GPS collars (Vectronic GPS-Pro 1D) from January 2005 to date in Eastern Italian Alps (Trentino Province, Monte Bondone area). Data are sent by the collars via GSM net, processed and downloaded as e-mail messages and finally converted to dbf files. We developed an integrated software environment to automatically store, associate geographic variables to and spatially analyse the data. ISAMUD (Information System for Analysis and Management of Ungulates Data) is mostly based on Open Source, Windows (Microsoft ®) and Linux operating softwares. The Geo-database PostgreSQL (http://www.postgresql.org/) and its spatial geographic extension PostGIS (http://postgis.refractions.net) are the core of the information system. Thanks to the latter, some geographic functions can be applied directly in the database, without invoking an external GIS, e.g. some categorical geographic variables (landuse, hunting districts...) can be associated to the localisations. Other more complex geographic features can be uploaded by the Open Source GIS GRASS (Geographic Resources Analysis Support System, http://grass.itc.it/), now available also in Windows version, via the interface Quantum GIS (QGIS) (www.qgis.org). Statistical and geostatistical analyses, including Home Range calculations, are carried out in R (http://www.r-project.org/), thanks to the numerous available packages, Adehabitat among all (http://cran.r-project.org/src/contrib/Descriptions/adehabitat.html), or to ad hoc developed functions. Results are then stored in the main geodatabase, to be available for further analyses. The database can be accessed by either PostgreSQL graphic interface, including PGADMIN III (http://www.pgadmin.org/) and ACCESS (www.microsoft.com/access/). The user-friendly data input/output format has been developed within the latter. The flexibility of the system allows the development of other modules and the applicability to different data sets from different species.