About 30% of all prescriptions issued in the USA, Canada and Europe contain either a herb, a purified extract or an active component derived from herbs. However, medical practitioners are often confused by conflicting information available on the safety and efficacy of herbs; herbal medicines are often co-prescribed without proper attention to adjustment of dosages. This reference guide treats the subject of herbal medicines in an integrated fashion with reference to pharmacognosy, pharmacology and toxicology. It will help to enable internists, phytotherapists, physicians, healthcare practitioners as well as students to understand why, when and how herbal medicines can be used in the treatment of diseases. Clinical and toxicological findings of herbs and their dosages are described. A great deal of pathology and therapeutic information is included. A large iconographic section can be of help when the identification of a herbal drug is in doubt. Many 2c tables as well as figures are included to clarify complex mechanisms and other information. The most important medicinal plants and drugs are illustrated with exceptional 4c plates.