Hydro-geochemistry of 135 water samples, collected at depths of 75 to 250 feet from tube wells in 1300 km2 area, indicates that I) the water is highly mineralized, with electric conductivity values > 22500 micromohs! cm in over 75 % of the area, and 2) the mineralization increases from northeast to southwest. The amounts of total dissolved solids (TDS) and sodium adsorption ratio (SAR) range from 515 to 26650 and 3 to 54 mg/ I, respectively, but in > 85 % of the area the TDS values are >11000 and SAR values >30. In most of the samples, pH varies between 7.5 and 8.3 (overall range 6.9 to 9.2) and organic content between 50 and 100 mg/ I (overall range 20 to 185). The dissolved constituents (Na, Mg, Ca, K, CI, SO., HCOJ, P and Cr) are dominated by Na (mostly 200-300 m eq/ I), Mg (variably high; 40-100 in 76 % analyses), CI (mostly 123-316) and SO. (55-216 m eq/ 1). Nearly 83 % of the analyses classify as sodium chloride type, and 17 % sodium sulfate type, with some Mg component in many. The data suggest that the groundwater belongs to a single, large aquifer. The concentration of dissolved solids and the salinity reflect the influence of geologic and hydrologic factors on the groundwater in the area. Much of the water is saline and seemingly associated with the highly soluble evaporite deposits occurring nearby. Only 10 % of the groundwater in the northeastern part of the area, occurring at shallow depth below 75 feet and probably diluted by seepage from canals and the Indus River, can be used for irrigation. Ninety percent of the groundwater shows hard type of incrustation.