Sideritis L. has a significant place among the other Lamiaceae genera owing to high percentage of endemism. The genus patterns are used as medicinal and herbal plants all over the world and Turkey. The plant is showed a strong antioxidant activities and it has diuretic effect. In this study, chemical composition of essential oil obtained by hydrodistillation of Sideritis dichotoma Huter was investigated by GC and GC-MS. The essential oils yield is 0.3 (v/w). Thirty nine components were comprised the 96.7% of the total essential oil extracted from the plant sample. The predominant compounds of plant were determined as b-pinene (28.5%), a-pinene (22.5%), limonene (4.6%) and a-terpinene (4.5%). The results were discussed with the genus patterns in means of chemotaxonomy and natural products.