This book, a clinical atlas of botulinum toxin(BoNT) therapy, is specifically focus on treating masseter muscle hypertrophy, sleep bruxism, facial asymmetry and headache. The first chapter of this book briefly discusses the history of BoNT, the molecular structure, toxin types, mode of action, and currently available indications. One of most common off-label use of BoNT in masseter muscle hypertrophy patients is presented in the second chapter. The following chapters review the literature (mostly from controlled and blinded studies) in sleep bruxism and headache. Many case reports are provided from my experience to illustrate injection techniques. The last chapter briefly addresses the immunogenicity and adverse effects. This book will become a valuable and beloved source of new knowledge and advice for interested readers all over the world.