Abstarct: The objective of this study was to investigate the mineralogy and geochemistry of tailings produced in Kooshk Pb-Zn mine, 45 km NE of Bafgh city. For this purpose, 30 tailing samples were collected and analyzed using standard methods. The obtained results indicate that pH value of the samples ranges from 1.2 to 7.6. The electrical conductivity of samples increased in samples with acidic pH values. The amount of calcium carbonate in tailing samples varied from 0.4 to 14% (mean value of 7.4%), indicating the low potential of tailing samples to neutralize acid pH. Geochemical data indicate that average concentrations of lead, zinc, arsenic, cadmium and sulfur (11175, 42070, 437, 101 and 53234 mg/kg, respectively) in the tailing samples are much higher than those in the upper continental crust. On the basis of mineralogical studies, pyrite was the most important sulfide mineral, which generates acid mine drainage at the Kooshk mine whereas quartz was the main mineral gangue in the tailings. Gypsum was the main secondary mineral in the oxidation zones of tailings indicating the productin of acid mine drainage in the studied samples. The most important iron oxide minerals were jarosite, natrojarosite, ferrihydrite, goethite, and magnetite. Geochemical investigations indicated that arsenic, cadmium, molybdenum, lead, and zinc have the highest enrichment factor. On the basis of values of the geoaccumulation index, the Kooshk tailings can be considered as the 7th class (highly polluted). Considering the ecological risk of potentially toxic elements, cadmium had the largest pollution level and induced the potential ecological risk at Kooshk mine. Potentially toxic elements and health risk assessment show that arsenic and lead is the most hazardous. Statistical data analysis shows that zinc, cadmium, cobalt, lead, antimony, nickel, molybdenum, arsenic, sulfur, manganese, and iron exhibit an anomalous behavior, suggesting environmental management of taillings producted in the Koosk Pb-Zn mine.