Groundwater samples from some localities in Qattara depression (especially the eastern part) were collected and subjected to chemical and isotopic analysis. The results of hydrochemical analysis are presented. Generally, the salinity ranges from relatively low (about 500 ppm) to very high values (29 g/l) whereas the Sabkha soil water shows an extremely high salinity reaching about 190 g/l. The environmental isotopic analyses of oxygen-18, deuterium and tritium show that groundwater in this region represents a mixture of several recharging types of water: marine water, paleowater and Nile water.