Generalized anxiety disorder (GAD) is a prevalent and impairing disorder, associated with extensive psychiatric and medical comorbidity. The current pharmacotherapies of anxiety are based on antidepressants and benzodiazepines. However, these drugs have limitations like slow onset of action, development of drug dependence, tolerance, amnesia and sedation. Therefore, the use of alternative therapies has increased substantially over the last decade. Kava is an intoxicating beverage made from the root extract of Piper methysticum and has been known as anxiolytic drug. The German health authorities banned kava extract containing products based on the suspicion of a potential liver toxicity. However, the risk-to-benefit ratio of kava extracts remains good in comparison to that of other anxiolytic drugs. To specialists in phytotherapy, this book provide detailed study to investigate the role played by amino acid neurotransmitters and acetylcholinesterase, in different rat brain areas, in the anxiolytic action of kava and the withdrawal effect of kava on them. Another aspect of this study is to demonstrate the effect of kava on some liver and kidney function parameters.