The hydrogeological properties of the Kurnub Group sequence in the central and northern Negev were reassessed following a broadly expanding data base. Over most of the study area, the Kurnub Group is composed of permeable horizons. The most pronounced aquiferous zone extends in the belt of the three breached anticlines (Makhteshim) toward the Dead Sea area whereas the least impervious zone was discerned north- and northwestward from this belt. The present-day relief at the base of the Kurnub Group is outlined by prominent structural highs. Major structural depressions are located close to the Dead Sea as well as in northwestern Negev and in the Coastal Plain of the Negev and its offshore. Three major subsurface structures i.e. the Dabbeshet, Gerar and the Judea blocks were formed along parallel, NE-striking Upper Cretaceous reverse faults (preceding normal faults). The amount of vertical displacements along these faults generally exceeds the thickness of impervious layers over- and underlying the Kurnub Group thus facilitating groundwater flow from the Arad Group into the Kurnub sequence and from the latter into the Judea Group aquifer. It appears that the Kurnub Group aquifer plunges from the structural highs of Ramon and Kurnub, toward the Dead Sea 3utlet, to the Sharsheret-Sedot Akiva basin and beneath the Coastal Plain. It also plunges westward to Shezaf and to the Sukkot-Julie low and further beneath the shelf. The new geological evidence and its hydrogeological implications provide solutions for various previously unexplained salinization processes and hydrochemical phenomena such as the ever increasing salinity in the Beer Sheva well-field, the high salinities and the particularly low U-concentrations in groundwater extracted from the Judea Group aquifer south of Beer Sheva, their thermal anomalies and high Fe+2 concentrations.