This book is part of the search for natural alternatives in the face of growing resistance to antimicrobial agents. It highlights the biological properties of eucalyptus (Eucalyptus globulus) essential oil. In vitro tests, carried out using the agar diffusion method, showed significant antimicrobial activity against several pathogenic strains, confirming the inhibitory potential of this essential oil. In addition, in silico studies based on molecular docking were carried out to assess the affinity of eucalyptus oil's major compounds with certain viral proteins. These results underline the interest of eucalyptus essential oil as a promising natural source for the development of new antimicrobial and antiviral strategies.