*This text was developed in consultation with national drug regulatory authorities within WHO’s Member States. It was also discussed during two informal consultations convened by the Division of Drug Management and Policies, WHO, Geneva, from 26 to 27 June 1991 and 29 June to 3 July 1992. The participants were: Ms M. Cone, International Federation of Pharmaceutical Manufacturers Associations (IFPMA), Geneva, Switzerland; Professor P. Dayer, International Union of Pharmacology (IUPHAR), Brussels, Belgium; Professor I. Darmansjah, University of Jakarta, akarta, Indonesia; Dr J.F. Dunne, Director, Division of Drug Management and Policies, WHO, Geneva, Switzerland (Joint Secretary); Dr Y. Hirayama, New Drugs Division, Ministry of Health and Welfare, Tokyo, Japan; Professor E. Hvidberg, University Hospital, Copenhagen, Denmark (Chairman); Dr J. Idänpään-Heikkilä, Associate Director, Division of Drug Management and Policies, WHO, Geneva, Switzerland (Joint Secretary); Mr R. Laderman, Center for Drug Evaluation and Research, Food and Drug Administration, Bethesda, MD, USA; Professor V.H. Lepakhin, Russian State Center for Drug Expertise, Moscow, Russian Federation; Dr P. Maurice, Ciba-Geigy, Basel, Switzerland; Professor J.O.M. Pobee, School of Medicine, Lusaka, Zambia; Mr M. Tsukano, New Drugs Division, Ministry of Health and Welfare, Tokyo, Japan; Dr S. Westman-Naeser, Medical Products Agency, Uppsala, Sweden; Professor A. Zanini, Institute of Biomedical Science, São Paulo, Brazil; Professor Zhu Jun-Ren, Shanghai Medical University, Shanghai, China.