Auto mechanics are occupational exposed to high doses of refined petroleum product which are known to contain considerable amount of polynuclear aromatic hydrocarbons. These compounds constitute great health hazard. In this study these exposed subjects and other unexposed subjects were screened for unmetablized PAHs. The study was carried out using Gas Chromatograph coupled with Mass Spectrometry Detector and the identification was based on retention time match and mass spectral match against those of standards. 25% of the exposed subjects were found to contain one polynuclear aromatic hydrocarbon or the other while one out of eleven unexposed subjects contains polynuclear aromatic hydrocarbon in their blood sample. The PAHs detected include anthracene, naphthalene and fluoranthene.