Abstract The chemical composition of the leaf oil of Schizonepeta annua (Pallas, Schischkin) from Altai Region, Siberia, which was obtained in 4.0% yield, was investigated by GC and GC/MS. The major components were thymol (48.1%), Î³-tepinene (18.1%), carvacrol (9.6 %) and p-cymene (9.0%). Key Word Index: Schizonepeta annua Lamiaceaeessential oil compositionthymolÎ³-terpinene