75CHEMICAL COMPOSITION AND ANTIBACTERIAL ACTIVITY OF THE LEAF OIL OF THYMUS VULGARIS LThe constituents of the leaf oil extracted by hydro distillation of Thymus vulgaris L, family, Lamiaceae from Ethiopia was examined by GC-MS. The yield of the yellowish oil was found to be be 0.97 % (w/w) in relation to dry weight basis. Eighteen chemical constituents were identified accounting for cent percent the leaf oil. The major terpenoids identified were thymol (31.977%), o-cymene (29.992%), carvacrol (14.541%), ç-terpinene (9.079%), linalyl anthranilate (4.762%), α-terpinene (1.756%) and 4-terpineol (1.464%). The leaf oil of Thymus vulgaris showed remarkable antibacterial activity against both gram negative (Escherichia coli) and gram positive (Staphylococcus aureus) bacteria.tsigereda@gmail.comResearch512015Hydro distillation,Thymus vulgaris L,Lamiaceae,Essential oil, Antibacterial activityTsige Reda,C.R.Unnithan,Kebede Taye,Legesset BrhaneDepartment of Chemistry, College of Natural and Computational Sciences, Mekelle University, Ethiopia,Department of Chemistry, College of Natural and Computational Sciences, Mekelle University, Ethiopia,Department of Chemistry, College of Natural and Computational Sciences, Mekelle University, Ethiopia,Department of Chemistry, College of Natural and Computational Sciences, Mekelle University, Ethiopia