Abstarct: The study area is located in Mayamey region in 65 Km east of Shahrood in 55˚ 23' to 55˚ 45' east longitude and 36˚ 16' to 36˚ 25' north latitude. Mayamey is situated in the end of east north of central Iran which include dry and sub-dry climate. Because of little precipitation and hot water condition, there is no surface water in this area and required water is concerned to groundwater. In the plains margins and higher regions, qanats are the most important device for extracting the ground water. To determined the qualitative and quantitative characteristic of qanats in Mayamey region, ten different qanats (Zeidr, Ebrahim-Abad, Mayamey, Panaftani, Ab-Marjan, Mohammad-Abad, Jodaneh, Kale-Sepidar, Narmposhteh and Armian) have been studied. Electrical conductivity, water temperature, pH and discharge measured for all qanats in situ and majer cations (Na, K, Ca, Mg) and anions (Cl, SO4, CO3, HCO3, NO3) measured in the laboratory. The obtained results indicate that the values of electrical conductivity and the concentration of major ions considerably depend upon the lithology of the catchment area of qanats. In order to evaluate the water quality of qanats, stiff, piper, wilcox and scholler digrams have been drawn. According to these diagrams, the water type varies in different qanats. Furthermore, the changes in discharge of qanats is a function of characteristic of catchment area of qanats, permeability and as well as the structure of qanats. Moreover, in order to evaluate the biological contamination of water, four water samples from the studied qanats (Ebrahim-Abad, Maymey, Mohammad-Abad, Jodaneh) were collected and transmitted to the lab for MPN test. The obtained results of this test show that all of them are relatively contaminated due to some open shafts and entrance of domestic waters to the qanats tunnels.