This book contains reviews covering studies in pharmacological research on the medicinal properties of essential oils and their chemical constituents. In addition, advances in the use of essential oils by inhalation route are also discussed. This book is intended for a broad readership, from curious undergraduates to pharmacologists, chemists, neuroscientists, health professionals, researchers in bioactive natural and synthetic products and from pharmaceutical industries. It is a valuable source for all people engaged in the study of medicinal plants.