Groundwater is the main source of potable water in most areas of Mazandaran province, like Sari and Babol city. Thus the safety of groundwater supplies is very important in these regions. Unfortunately attention to groundwater quality has remained limited in Iran. In recent years, the growth of industry, technology, population, and water use has increased the stress upon both land and water resources of Mazandaran province. The main pollutants of groundwater in Mazandaran province are domestic, industrial and agricultural wastewater discharges. In addition, contribution of municipal and rural solid wastes in deterioration of groundwater quality of the Mazandaran province is considerable. The quality of several water wells in Mazandaran province was investigated in this research. In tested water wells, the concentrations of Cu, Cr, Zn and NO3 are within WHO standard limits, but Pb, Se and Cd concentrations are often exceeding the WHO maximum permissible standard values. Results show that the current quality of groundwater in Mazandaran province does not present immediate health related concerns. However, the quality of water wells in Mazandaran province is not reliable because of relatively high rate of various pollutants discharges into groundwater resources. Consequently, establishment of both monitoring programs and appropriate regulations to minimize uncontrolled discharges into groundwater resources is necessary for conservation of this valuable source of water supply in Mazandaran province.