The FAO/WHO Manual on development and use of FAO and WHO specifications for pesticides contains general principles and methodologies of the work undertaken by JMPS, is the continuous evaluation of new scientific developments and guidance documents. The Manual gives the historical background of the operation of the JMPS and describes the purpose of the work. The Manual is also used by countries as a guidance document in setting pesticide specifications. This 3rd revision of the Manual contains new methodologies/principles developed in recent 5 years and incorporates the current working principles applied by the JMPS.