Abstarct: The Ahangaran mine is one of the most important producers of Pb and Zn in Iran. This mine is located 95 km SE Hamedan. The purpose of this study was to evaluate the contamination of potentially toxic elements in tailings of the Ahangaran mine. For this purpose, 14 tailing samples were collected. The physicochemical properties of the samples (including pH, calcium carbonate contact, texture and CEC) were measured using standard methods. The concentration of potentially toxic elements was determined using ICP-OES instrument. The mineralogy of the samples was investigated using XRD analysis. On the basis of the obtained results, the concentration of elements in the samples was in the range of 5530-12202, 300-28612, 1.1-515, 56-229, 14.5-40.5 and 8.4-12.4 mg‏‏/kg for Pb, Zn, Cd, Cu, Ag and As, respectively. The concentration of elements was higher than the average crust composition. The calculation of geo-accumulation index (Igeo), enrichment factor (EF), contamination factor (CF), degree of contamination (MCd), pollution load index (PLI), index of contamination (PI), integrated pollution index (NIPI), hazard quotient (HQ) and total hazard index (HI) shows that the studied samples are highly polluted with potentially toxic elements. The high positive correlation coefficients between Fe, S, Sb, Mo, Zn, Ag, Cu and As was probably due to the presence of potentially toxic elements in sulfide minerals. The results of XRD analysis confirms this conclusion. Regarding the high concentration of potentially toxic elements in the tailings of the Ahangaran mine, the remediation measures are necessary to reduce the negative impact of mining operations on the environment.