This paper deals with the estimation of realistic potentials of the different renewable energy resources in Hungary. Within the framework of the Renewable Energy Subcommittee of the Energy Committee of the Hungarian Academy of Sciences a study of scientific merit has been elaborated in order to calculate the magnitude of renewables for the entire country. The paper contains in details the concept, the applied conditions, the meteorological and statistical data and the available databases which may vary substantially according to the different sort of renewable energy resources. The results obtained for the different resources have been discussed and compared to each other avoiding some overlapping may occur in some areas. The main fields studied are as follows: Direct use of solar energy - active solar thermal systems; - passive solar thermal systems; - solar photovoltaics system; - agricultural solar thermal systems. Indirect use of solar energy - hydro systems; - wind energy systems; - biomass. Geothermal energy. Further step is to take into account the aspects of the practical applications, along with the economical and financial conditions and circumstances.