Methyl tert-butyl ether, ethyl tert-butyl ether and tert-amyl methyl ether are oxygenated compounds added to gasoline to enhance octane rating in replacement of alkyl–lead compounds. In the present study the excretion of urinary methyl tert-butyl ether, ethyl tert-butyl ether and tert-amyl methyl ether were evaluated as biomarkers of exposure to gasoline. With this aim, 10 policemen engaged in traffic control, 10 gas station workers and ten occupationally non-exposed persons were investigated. Spot urine samples were obtained prior to and at the end of the work shift from each subject. The urinary levels of oxygenated ethers were determined by using head-space gas chromatography and mass spectrometry detection. There were significant differences among the mean urinary concentrations of methyl tert-butyl ether in pre-shift samples of gas station workers (1193 ng/L), policemen (734 ng/L) and occupationally non-exposed persons (49 ng/L). The mean urinary concentrations of methyl tert-butyl ether and tert-amyl methyl ether differed significantly among post-shift samples of gas station workers (16636 and 8655 ng/L), policemen (14458 and 1472 ng/L) and occupationally non-exposed persons (324 and 59 ng/L) (ANOVA: p<0.05 and Kruskal-Wallis test: p<0.05). There was a significant difference in methyl tert-butyl ether concentrations between job categories (p<0.05 by ANOVA and Kruskal-Wallis test), and gas station workers and policemen were found to be probably the most exposed groups in this study.