Abstarct: This study was conducted to investigate the effect of gold mineralization on the quality of the groundwater in Hired Gold Mine Zone. The region (almost 128 km2) is located in south of Birjand, Southern Khorasan province. The average annual air temperature is 16.4 degree of centigrade and average annual rainfall in this region is 171.5 mm and the area is in the arid climate. Geology of area is included Jurassic sedimentary rocks, Cretaceous, Paleosen and volcanic rocks which composed Andezit-Dasit with age of Eosen. Moderate acidic Granotoeidic bodies Type-I included Diorit, Grano-Diorit and Granit with age of Oligosen are intruded to this section. Mineralization of Au, Sb and As is caused by hydrothermal flows which involved silisic vein. The mineral veins are the most important sources of pollution by heavy mextals as well as the cause of distribution of elements and heavy mextals in the area. The main mineralization zone is located in the northern slope of Siah-Kamar Mountain (center of region). For sampling, the position of wells and qanats were determined by field investigations. In order to measure the physico-chemical parameters including the important anions and cations and the concentration of elements and heavy mextals, the water samples were analyzed through the standard methods and ICP-MS techniques. To investigate the relationship between the lithology and the groundwater quality in the area, the rock samples were collected. 19 thin sections and 7 polished sections were prepared and studied by polarizing microscope. Some rock samples were analyzed by ICP-MS techniques. The results showed that the concentration of gold was 0.6 to 6.8 ppb, arsenic 2.6 to 1835 ppm, bore 38 ppm, mercury 21 ppb, sulfur 70 ppm, selenium 0.6 ppm and strontium 34.5 to 362.4 ppm and reaches the maximum concentrations in the vicinity of the mineralization area. Concentration of chloride, sulfate and sodium in all of water samples were higher than the standard values. In the water samples, the concentrations of arsenic was 1426 ppb, bore 2778 ppb, sulfur 349 ppb, selenium 19.4 ppb, strontium 13.53 ppm and mercury 1.5 ppb. At the end of the wet season, concentrations of Cl, SO4, Na, As, B, Cr, Mo, S, Se and Sr decreased while the concentrations of Mg, Ca, Mn, Sb and Zn were increased. High correlation in water samples between Cu with S, Na with Sr, SO4 with B and Mg with SO4 indicate a similar geochemical behavior of these elements. Offsetting the distribution of elements in iso-concentration maps of water and rocks on the geological map of the region, mineralogical studies which confirm the presence of arsenopyrit, pyrite and tourmaline in the area, and variety of alterations in the region, indicate the effects of racks and minerals on groundwater quality. In overall, the water resources in the area are contaminated by Cl, SO4, Na, As, B, Se and Hg and are not suitable for drink.