The first volume of the WHO monographs on selected medicinal plants, containing 28 monographs, was published in 1999. This second volume contains an additional collection of 30 monographs describing the quality control and uses of selected medicinal plants. Each monograph contains two parts, the first of which provides pharmacopoeial summaries for quality assurance purposes, including botanical features, identity tests, purity requirements, chemical assays and major chemical constituents. The second part, drawing on an extensive review of scientific research, describes the clinical applications of the plant material, with detailed pharmacological information and sections on contraindications, warnings, precautions, adverse reactions and dosage. Also included are two cumulative indexes to both volumes. The monographs are intended to promote international harmonization in the quality control and use of herbal medicines and to serve as models for the development of national monographs or formularies. They will be a valuable scientific reference for drug regulatory authorities, physicians, traditional practitioners, pharmacists, manufacturers and research scientists, and will also be of interest to the general public.