The determination of metabolites of benzene, toluene, ethylbenzene, and xylenes in urine has been used to assess human exposure to these compounds. The analyses of urine samples for these metabolites are tedious and time consuming. The determination of unmetabolized individual compounds in urine has been studied previously with some success. A simultaneous determination of several unmetabolized VOC compounds in urine by thermal desorption-gas chromatography was conducted to assess the exposure of smokers and nonsmokers to these compounds. The method of thermal desorption-GC was sensitive enough to detect a significant difference in exposure levels due to the contribution of light smoking in the environmentally-exposed group.