The results of geochemical studies of groundwater and brines of the pre-jurassic complexes of the Fore-Yenisei sedimentary basin are presented. It is shown that the region under investigation is characterized by a transitional type of the hydrogeological structure of the Paleozoic and pre-Paleozoic sections between the West Siberian and Tunguska artesian basins, with all the ensuing consequences: groundwater occurrence, sedimentation, chemical and gas composition, gas saturation, vertical zoning and others. Groundwaters and brines with sodium chloride composition with the total mineralization of 48 to 209 g/dm3 are predominant in the pre-jurassic complexes. A normal type of vertical hydrogeochemical zoning is developed in the region. The upper part of the section is washed with ancient infiltrogenous waters to a depth of 2-2,5 km. Deeper lie the ancient sedimentogenous waters of the middle stage of metamorphism.