A total of 11 PM2.5 samples were collected from October 2003 to October 2004 at 8 sampling sites in Beijing city.The PM2.5 concentrations are all above the PM2.5 pollution standard(65μg m(-3))established by Environmental Protection Agency,USA(USEPA)in 1997 except for the Ming Tombs site.PM2.5 con-centrations in winter are much higher than in summer.The 16 Polycyclic aromatic hydrocarbons(PAHs)listed as priority pollutants by USEPA in PM2.5 were completely identified and quantified by high perfor-mance liquid chromatography(HPLC)with variable wavelength detector(VWD)and fluorescence detector (FLD)employed.The PM2.5 concentrations indicate that the pollution situation is still serious in Beijing.The sum of 16 PAHs concentrations ranged from 22.17 to 5366 ng m-3.The concentrations of the heavier molecular weight PAHs have a different pollution trend from the lower PAHs.Seasonal variations were mainly attributed to the difference in coal combustion emission and meteorological conditions.The source apportionment analysis suggests that PAHs from PM2.5 in Beijing city mainly come from coal combustion and vehicle exhaust emission.New measures about restricting coal combustion and vehicle exhaust must be established as soon as possible to improve the air pollution situation in Beijing city.