The Red River delta plain of 17.000 km2 in area, is composed of unconsolidated Quaternary sediments overlying Neogene sediments and ancient basement; it is one of most important social-economic areas in ViÖt Nam. The development of one area depends much on water resources in general and groundwater in particular. Hence, since the begining of 90's years the Division of Hydrogeology - Engineering Geology of North ViÖt Nam has been constructing the groundwater regime monitoring network with 78 regional points, 3 water balance yards, 6 lines for studying the relationship between groundwater and surface water, with a total amount of 211 monitoring works. The obtained results reflect the real picture on groundwater environment in the study area. The lowering of groundwater level occurs in many places of the plain, especially in Hµ Néi. Hence the saline intrusion, groundwater pollution and land-subsidence have been occurring leading to groundwater decrease. So, serious problems can happen if the groundwater decrease is not controlled and its exploitation is carried out in rational planning.