Abstract The water-distilled oils from two chemotypes of Thymus leucostomus var. leucostomus, an endemic plant of Turkey were analyzed by GC/MS. One chemotype contained carvacrol (21.59%), p-cymene (17.80%) and thymol (14.10%); and the other chemotype contained Î±-terpinyl acetate (23.80%), borneol (12.85%), linalool (13.67%) and thymol (11.31%) as major constituents. Key Word Index: Thymus leucostomusvar leucostomus Labiataeessential oil compositionÎ±-terpinyl acetatecarvacrol