Abstarct: The study area is located in Sanandaj-Sirjan zone and Isfahan-Malaxyer lead-zinc mineralization belt. From environmental point of view, this area, has a high risk for entering of potentially toxic elements in to groundwater resources. In recent years, mining activities have increased in southeast of Najaf Abad plain, threatening the groundwater quality of this region. In order to study hydrochemical characteristics of groundwater resources, 22 samples from agricultural wells were collected and hydrochemical parameters and concentrations of Cd, Co, Cu, Ni, Zn and Pb were measured. The average value of pH, EC and TDS is 7.2, 6298.9 μmhos/cm and 5237.5 mg/l, respectively. baxsed on the values of EC, TDS and major ions concentration, the study area is divided into three zones of A (at the west), B (Central part of the area and close to tailing dams) and C (at the east). Type of water in the zones of A, B and C, are Na-Cl, Ca-SO4 and Na-SO4, respectively. The concentration of Na, Ca, SO4 and potentially toxic mextals in the zones B and C, increased due to seepage of wastewater from processing tailing dams. Ion exchange (in zone A), and reverse Ion exchange (in the zones B and C) increasing sodium and calcium, respectively. The average concentration of sodium, calcium, magnesium, potassium, chloride, and sulfate in groundwaer samples are respectively 9.6, 7, 1.6, 1.4, 6.4 and 8.3 time greater than WHO standard for drinking water, respectively. The average concentration of cadmium, lead, arsenic, zinc, and nickel in the groundwaer samples are 100, 58, 28.3, 15.3 and 2.4 time greater than WHO drinking water standard, respectively. The results of statistical analysis shows the mining and processing activities (anthropogenic factors) and interaction of water with rocks in the aquifer (natural factors), are the main factors for changing hydrogeochemical parameters in the study area. In general, seepage through tailing dams in which wastewater enriched by sodium cyanide, Potassium Amyl Xanthate (PAX) in the processing of lead and zinc, as well as, dissolution of minerals in the aquifer, increase the concentration of major ions and potentially toxic elements in groundwater of Irankouh area.