The composition of volatile organic compounds (VOCs) was anlyzed for major emission sources such as vehicle exhaust, gasoline and diesel vapor, organic solvent vapor, and butane fuel gas. Low carbon-numbered hydrocarbons were found to be the dominant components of gasoline vehicle exhaust. In gasoline evaporative vapor, the predominant constituents were found to be butane and iso-pentane regardless of ambient air temperature. In case of diesel evaporative vapor was similar to those of gasoline evaporative vapor. The composition of organic solvent vapor from painting, ink and petroleum consisted mostly or aromatic compounds such as toluene and m, p, o-xylene. The hydrocarbon fraction of butane fuel gas. which is used by portable bunner, consisted mainly of propane (34%) and butane(70%).