Artemisia mesatlantica is an endemic species of Morocco, rare and endangered which is widely used in traditional medicine. This present work deals with the chemical composition and the antibacterial and antifungal efficacy of the EO of the domesticated Artemisia mesatlantica. The average yield of essential oil of the aerial part (stems, leaves and flowers) of this latter is 0.97%. Among the chemical constituents of the essential oil of A. mesatlantica are β-thujone (77.77%) which is predominant, followed by 1.8-cineol (6.31%), and camphor (3.52%) the other constituents are with small percentages. About the antimicrobial test, four bacterial strains (Escherichia coli, Bacillus subtilis, Staphylococcus aureus and Micrococcus luteus) and three fungal strains (Aspergillus niger, Penicillium digitatum, Penicillium expansum) were chosen for their pathogenicity and for their frequent involvement in food contamination. The bioassay shows that the minimum inhibitory concentration of the growth of the following microorganisms: Escherichia coli, Staphylococcus aureus, Micrococcus luteus, Penicillium expansum, Penicillium digitatum is 1/500 v/v whereas Bacillus subtilis and Aspergillus niger is 1/250 v / v.