Aromatherapy treatments are widely available and often offered in hospitals, while essential oils can be purchased in every town. This change in attitude has bought so many benefits, but it is worth also considering the dangers that have emerged with the commercialization of aromatherapy. Although essential oils are all wholly natural substances, they can be subject to adulteration, so it is important to always buy them from a reputable supplier. It is also vital to check that any specific safety guidelines are followed with care at home. The Scientific trials and clinical research have continued to confirm the potentiality of essential oils, they have become increasingly respected within the medical arena. This has been accompanied by a steady increase of public interest in holistic therapies and a sociological trend towards embracing all things ‘natural’ over the past two decades in Europe and the United State. Essential oils and their volatile constituents are used widely to prevent and treat human disease. The possible role and mode of action of these natural products is discussed with regard to the prevention and treatment of cancer, cardiovascular diseases including atherosclerosis and thrombosis, as well as their bioactivity as antibacterial, antiviral, antioxidants and antidiabetic agents. Their application as natural skin penetration enhancers for transdermal drug delivery and the therapeutic properties of essential oils in aroma and massage therapy will also be outlined.