Abstarct: The aim of this study is to evaluate the pollution of heavy mextals and polycyclic aromatic hydrocarbons (PAHs) in the street dust of Semnan urban area. Street dust particles are a suitable indicator to evaluate pollution in urban areas. For this purpose, 19 samples were taken to measure the concentration of heavy mextals and PAHs and discriminate the origin of these compounds and also their impacts on human health. Dust samples were analyzed by ICP-MS and GC-MS for heavy mextals and PAHs, respectively. The obtained results showed that the concentration of Pb, Zn and Cu elements among the sampling stations is significantly high. The average concentration of studied elements is arranged in order of Zn> Pb> Cu> Ni> Cr> As. The results of the calculation of geochemical indices showed that in the sampling stations, the pollution degree of dust samples is significantly higher than in terms of Pb, Zn and Cu. The results of the human health risk assessment showed that the non-carcinogenic risk of HQ values for Pb in all stations through the ingestion pathway for children is greater than one. The non-carcinogenic risk value of the total HI from the ingestion for children across all stations was also obtained greater than one. The carcinogenic risk of As, Cr, Ni and Pb from ingestion, inhalation and skin contact is negligible in both groups of adults and children. The statistical analysis of the data showed that Pb, Cu, As and Zn have mainly anthropogenic origin whereas Cr, Ni are probably derived from natural origin. The descxriptive statistics of PAHs showed that the highest average concentration is related to anthracene and the lowest concentration is related to indene. Evaluation of PAH pollution in the sampling stations showed that S4, S5, S9 and S8 stations fall within the severe pollution category. Finally, it was found that the main source of cyclic hydrocarbons in the studied street dust is from mobile and pyrogenic sources resulting from incomplete combustion of liquid fossil fuels.