Comparative study between the chemical composition of the essential oils of Asteriscus maritimus and Asteriscus spinosus from Western Algeria have been investigated. Chemical variability of the essential oils of both species was reported for the first time using gas chromatography/retention indices (GC/RI) and GC-mass spectrometry (GC/MS). A total of 86 compounds were identified in A. maritimus collective essential oil and 76 compounds in A. spinosus collective essential oil. Intra-species variations of the chemical compositions of essential oil from eighteen Algerian samples of various locations of both species were also investigated using statistical analysis. A. maritimus essential oils were characterized by T-cadinol (34.2â16.1%), p-cymene (30â15.1%), Î±-pinene (13.9â2.8%), bornyl acetate (8.7â5.3%) and Z-phytol (7.8â2.4%), as the major compounds. The main compounds of A. spinosus were Î±-cadinol (19.8â7.3%), Î²-pinene (17.6â12.9%), hexadecanoic acid (13.4â4.1%), T-cadinol (10.3â3.5%) and Î´-cadinene (8.2â3.9%).