Thyme is a wild plant naturally found in the AL-Qadmous area at varying altitudes up to more than 1000 m above the sea level. Essential oil of thyme dry leaves was extracted by water distillation method using Clevenger apparatus. Gas Chromatography – Mass Spectrometry technique (GC-MS) was used to determine essential oil content of Thymol, Carvacrol and Pinene compounds. The results of chemical analysis show that Thymol percentage ranged between 1.28 and 4.86 % and that of Carvacrol ranged between 78.08 and 83.27 %, while Pinene content ranged between 11.86 and 20.65%. Statistical analysis shows significant differences between the compounds contents studied in the three sites. The highest percentage of both Thymol and Carvacrol is recorded at A3 site (320 Meter) above sea level. On the other hand A1 site (200 Meter) above sea level has the highest value of Pinene compounds compared with the other sites.