T HE EGYPTIAN Western Desert is considered as one of the most arid regions in the country. Recently, expanding developmental activities are invading the study area in El Farafra Oasis especially agriculture. The groundwater in the Western Desert represents the main source of water where the increase in groundwater extraction rates could affect the future development plans negatively. Accordingly, this article is concerned with the study of the hydrogeological characteristics of the Nubian Sandstone Aquifer System (NSAS) and the effect of groundwater exploitation on aquifer potentiality. The study includes well inventory, measuring piezometric heads, measuring salinity of groundwater samples as well as conducting and analysing of pumping/ recovery tests on selected wells. Two hydrogeological cross sections were constructed based on the data of new drilled wells. The regional groundwater flow direction in the NSAS is from southwest to northeast. However, local groundwater flow from east to west is evidenced due to extensive groundwater extraction in the west. The analyses of pumping tests were carried out to estimate the hydraulic properties such as the hydraulic conductivity (K), the transmissivity (T) and the storativity (S). The average K is about 7.1 m/d, while the average T is about 2704 m 2 /d. The storativity reached about 0.0002. The potentiality of the NSAS varies from high potential in the middle and the eastern parts, to moderate potential in the western parts. A groundwater development plan is recommended to avoid the deterioration of the NSAS in the coming decades.