In this paper regional climate change estimations for the Carpathian Basin (located in Eastern/Central Europe) using three different methods are compared, namely, stochastical downscaling technique nested in coupled ocean-atmosphere GCMs (developed at the Department of Meteorology at the Eotvos Lorand University), regional dynamical climate modeling method (model PRECIS of the UK Met Office, Hadley Centre), and an upwelling diffusion energy balance model combined with GCM outputs and IPCC emission scenarios (MAGICC/SCENGEN, developed by Wigley et al., NCAR). The IPCC Third Assessment Report suggests that eastern and central European countries could become highly vulnerable to global warming, this hypothesis is tested using the above listed methods. Our investigations cover the entire region and focuses on two subregions of the Carpathian Basin: (1) Great Hungarian Plain, (2) watershed of the Lake Balaton. Severe shortage of precipitation and unusual intense flood events occured in the last few decades in both areas, therefore, ecosystems must face to high risk of environmental change. The Great Plain is the largest agricultural area in Hungary where high variability of floods and droughts cause severe damages in crop yields and human settlements, as well. The largest lake in Western and Central Europe is the Lake Balaton with its uniquely shallow 3.3 meter depth on average. In the last few years, the mean water level has decreased by 60-80 cm several times for a few months or even half a year period. The stochastical downscaling method includes large-scale circulation of the atmosphere, and also, it is able to represent the linkage between the local surface variables and large-scale circulation. Seasonal and annual changes in temperature and precipitation have been determined for Hungarian stations in case of the 2×CO₂ climate and compared to historical time series. Furthermore, the four main IPCC SRES emission scenarios have been compared and GCM outputs have been analysed using the MAGICC/SCENGEN package in order to project climate conditions (inlcuding daily mean, maximum and minimum temperature, and precipitation) for the 21st century. Spatially more detailed projections (for 2071-2100) of climate parameters are provided for the Carpathian Basin by using the regional climate model of PRECIS (at 25 km horizontal resolution, 19 vertical levels).