Emission of dust-fall particles in western Iran has been considered as one of the most important environmental issues in recent years. Additionally, presence of heavy metal in these particles due to their toxicity and health problems has been an issue of interest by researches. Therefore evaluation of the contamination level of this kind of pollution and then determination of proper management strategies for controlling their emission is very important. In fact, the main scope of this research was to evaluate the contamination level of heavy metals in dust-fall particulates precipitated in western Iran using Geo-accumulation index (Igeo). In this research these particles were sampled through passive deposit gauge method for a period of one year, from April 2010 to March 2011, in Sanandaj city, western Iran, where has been reportedly the third highly polluted city of the world in 2010 for dust-fall particles. The results demonstrated that mean ± SD of the concentration of heavy metals were 14003.570±915.3 for Fe, 497.731±29.817 for Mn, 61.307±5.414 for Cu and 18.287±1.955 for As in mg/Kg based on dry weights of dustfall particles. Also the analysis of the Geo-accumulation index showed that the maximum amounts of Igeo values were -1.751 for Fe, -0.63 for Mn, 0.848 for Cu and 1.249 for As, which were evaluated as uncontaminated for Fe and Mn and moderate contamination Cu and As.