Squalene owns a long tradition of research since its first publication backs to 1926. To provide a state of the art revision, this book has collected published works regarding: in vivo and in vitro antioxidant properties, the bioavailability in animal models and in humans, the plasma and intracellular transport of this lipophilic molecule, its ability to neutralise different xenobiotics, its anti-inflammatory, anti-atherosclerotic and anti-neoplastic properties, its presence in skin lipids and its role in skin ageing and pathology, and finally its use to boost antigenicity of vaccines.