Abstract: Heterogeneity of levels of socio-economic development of countries or country's different regions is undesirable. For the sake of sustainable development of a country or group of countries it is important to elicit relative levels of development of country's regions or different countries, and to find the weakest indicators of their development. Socio-economic development of a country or group of countries depends on a variety of factors. Statistics Department of Lithuania provides annual data describing the state of all 10 counties of Lithuania by 162 criteria. 60 criteria describe economic development, 94 describe social development, and finally, ecological state is described by 8 criteria. Prevailing in literature comparative analysis by separately selected criteria, as important as GDP per capita, often does not provide an extensive picture of quality of life of country's citizens. A comprehensive approach is required for evaluating of level of development of countries or country's regions. A suitable tool, which promptly provides quantitative evaluation of level of development of country's regions, provides results in a clear comprehensible form, and comprises the whole variety of important multi-dimensional criteria is multiple criteria decision-making (MCDM) methods. Experienced experts evaluate weights of importance of criteria used in the research, keeping in mind the major aim of the evaluation. Weights and values of criteria are comprised into a single cumulative criterion of a MCDA method. Comparative analysis of evaluation over a lengthy period of time allows to analyse dynamics of development of the regions, and to elicit levels of dependence of different criteria on the general level of development and welfare. MCDM methods allow revealing weaknesses of development of every region and provide a strong support for decision-makers and politicians for their effective actions intended for sustainable development of regions.