ABSTRACT: The groundwater research represents a long tradition in the Czech Republic. It has been continuing since late 19th century with the main object concerning abundant drinking water supply for large cities. After 1918 in Czechoslovakia, the groundwater research was performed by the National Hydrological Institute (present the T. G. Masaryk Water Research Institute) and by the National Geological Survey (present Czech Geological Survey). Systematic regional hydrogeological research of the Czechoslovak territory was performed between the late 1960s and early 1990s. The research summarizes results of hydrogeological mapping and investigations. The presented paper offers an overview of basic regional hydrogeological projects implemented in the Czech Republic.