Patients with chronic diseases such as cardiovascular diseases, chronic respiratory diseases, and neurological diseases have been shown to benefit from treatments such as aromatherapy in addition to medication. Most chronic diseases are caused by chronic inflammation and oxidative stress as well as harmful factors. Eucalyptol (1,8-cineole), a terpenoid oxide isolated from Eucalyptus species, is a promising compound for treating such conditions as it has been shown to have anti-inflammatory and antioxidant effects in various diseases, including respiratory disease, pancreatitis, colon damage, and cardiovascular and neurodegenerative diseases. Eucalyptol suppresses lipopolysaccharide (LPS)-induced proinflammatory cytokine production through the action of NF-κB, TNF-α, IL-1β, and IL-6 and the extracellular signal-regulated kinase (ERK) pathway, and reduces oxidative stress through the regulation of signaling pathways and radical scavenging. The effects of eucalyptol have been studied in several cell and animal models as well as in patients with chronic diseases. Furthermore, eucalyptol can pass the blood-brain barrier and hence can be used as a carrier to deliver drugs to the brain via a microemulsion system. In summary, the various biological activities of eucalyptol such as its anti-inflammatory and antioxidant properties, as well as its physicochemical characteristics, make this compound a potentially important drug for the treatment of chronic diseases.