chemical composition of the essential oils of three subspecies of algerian thymus munbyanus boiss. & reut. (subsp. abylaeus, subsp. ciliatus and subsp. coloratus) aerial parts have been investigated. gc and gc/ms analysis allowed the identification of sixty-eight compounds accounting for 99.3%, 99.7% and 98.2% of collective essential oils of three subspecies. the main components of three collective essential oils were: -terpinyl acetate (51.7%), -terpineol (9.7%), borneol (6.8%) and bornyl acetate (5.2%) for subsp. abylaeus; carvacrol (65.7%), -terpinene (13.6%) and p-cymene (7.9%) for subsp. ciliatus and camphor (25.9%), myrcene (16.9%), 1,8-cineole (6.5%) and camphene (6.2%) for subsp. coloratus. intra-species variations of chemical compositions of essential oil from thirty-five algerian samples were also investigated using statistical analysis. essential oils samples were discriminated in three main clusters confirming relation between the chemical compositions and taxonomical differentiation between the three subspecies. these results confirm chemotaxonomic differentiation of all subspecies of t. munbyanus.