This report presents the recommendations of the fortieth WHO Expert Committee on Drug Dependence (ECDD). The ECDD is responsible for the assessment of psychoactive substances for possible scheduling under the International Drug Control Conventions. The ECDD reviews the therapeutic usefulness, the liability for abuse and dependence, and the public health and social harm of each substance. The ECDD will advise the DirectorGeneral of WHO, to schedule or to amend the scheduling status of a substance. The Director-General will, as appropriate, communicate the recommendations to the Secretary-General of the United Nations, who will in turn communicate the advice to the Commission on Narcotic Drugs (CND).