THE COMMISSION ON WORLD STANDARDS in Clinical Pathology of the World Association of Societies of Pathology (COWS of WASP) organizes symposia from time to time with a view to promote understanding of statements concerning the results of medical examinations. International symposia are organized every four years. The first international symposium on quantities and units took place in 1972 in Munich, Germany, the second in 1976 in Gaithersburg, Maryland, and the third in 1980 in Paris, France. This third symposium was sponsored by the Bureau International des Poids et Mesures, Coultronics, S.A., and Du Pont de Nemours, Ltd., The German Institute for Standardization and Documentation in Medical Laboratories (INSTAND), and by the United Nations Educational, Scientific and Cultural Organization (UNESCO). To this symposium were invited: Bureau International des Poids et Mesures (BIPM); Commission on World Standards of the World Association of Societies of Pathology (COWS of WASP); International Committee for Standardization in Hematology (ICSH); International Federation of Clinical Chemistry (IFCC); International Standard Organization (ISO); International Union of Immunological Societies (IUIS); International Union of Pure and Applied Chemistry (IUPAC); United Nations Educational, Scientific and Cultural Organization (UNESCO); World Health Organization (WHO); and World Medical Association (WMA). Personal invitations were given to selected scientists; those present included: Prof. Dr. A. Alissy, BIPM, Paris, France; Mrs. I. Batty, IUIS, London, United Kingdom; Dr. Ch.-G. de Boroviczeny, Moderator, COWS of WASP, INSTAND, Berlin, FDR; Prof. Dr.