This report presents the recommendations of an international group of experts convened by the World Health Organization to consider matters concerning the quality assurance of pharmaceuticals and specifications for drug substances and dosage forms. Of particular relevance to drug regulatory authorities, the report discusses activities related to the further development of The international pharmacopoeia, as well as simple test methodology, the stability of dosage forms, good manufacturing practices, legal and administrative aspects of the functioning of national drug regulatory authorities, and quality assurance in the supply system. The report is complemented by numerous annexes, including guidelines for the graphic representation of chemical formulae, lists of available International Chemical Reference Substances and International Infrared Reference Spectra, general recommendations for the preparation and use of infrared spectra in pharmaceutical analysis, and guidelines on stability testing of pharmaceutical products. In the context of good manufacturing practices, guidance is provided on the validation of manufacturing processes and for the manufacture both of investigational products for clinical trials and of herbal medicinal products. The final annexes contain guidelines adopted or endorsed by the Committee on registration requirements to establish the interchangeability of multisource pharmaceutical products, implementation of the WHO Certification Scheme on the Quality of Pharmaceutical Products Moving in International Commerce, the assessment of herbal medicines, and import procedures for pharmaceutical products.