The Nairobi Decision on Preferential Rules of Origin (RoO) for Least Developed Countries (LDCs) established for the first time a set of multilaterally agreed guidelines to facilitate optimal use and benefits from the preferential market access granted to LDCs by WTO Members. This brief note undertakes a focussed assessment of notifications received so far, based on three out of the four criteria that define substantive transformation as set out in the Nairobi Decision, i.e. change of tariff classification; specific working or processing and underlying cumulation and certification procedure, as reported in the notifications submitted by preference granting countries.