Objective: To extract and identify the main constituents of the essential oil of Cotula cinerea (Del.) (Asteraceae family) from southwest of Algeria. Methods: The essential oils obtained by hydrodistillation, from the aerial parts of the endemic plant Cotula cinerea which was collected in the region of Sahara from southwest of Algeria, were analyzed by gas chromatography-mass spectrometry. Results: A total of 33 compounds were identified representing 98.66% of the oil. The main compounds were (E)-citral (24.01%), limonene epoxide cis- (18.26%), thymol methyl ether (15.04%), carvacrol (15.03%), trans-carveol (13.79%), carvone (3.06%) and trans-piperitol (2.54%). Conclusions: The main constituents in essential oil of the aerial part of the plant from southwest of Algeria were different from that collected from southeast of Algeria or in Morocco.