In order to understand the average concentrations of ambient volatile organic compounds (VOCs) in the urban atmosphere of Beijing, a diffusive sampling device (DSD-voc) was used to adsorb VOCs. The adsorbates were analyzed by gas chromatography/mass spectrometry (GC/MS) using a thermal desorption cold trap injector (TCT) and determined according to the EPA Method TO14. Sampling for 24 h a day was conducted at five sites continuously for one week from October 24 to 30, 2006. Sixteen VOCs were detected and the weekly average values were calculated for each site, with the maximum and minimum VOC concentration values of 135.1 and 77.3 mu g/m(3). Benzene, toluene, ethylbenzene, m,p-xylenes and o-xylene (BTEX) account for almost three quarters of the detected VOCs and these correlate well with each other among sites, suggesting the main emission sources are vehicular emissions.