This report presents the recommendations of the WHO Expert Committee responsible for updating the WHO Model Lists of Essential Medicines. It contains a summary of the Committee's considerations and justifications for additions and changes to the Model Lists, including its recommendations. Annexes to the main report include the revised version of the WHO Model List of Essential Medicines (17th edition) and the WHO Model List of Essential Medicines for Children (3rd edition). In addition there is a list of all the items on the Model Lists sorted according to their Anatomical Therapeutic Chemical (ATC) classification codes.An additional annex covers the Report of a Supplementary Meeting of the Expert Committee on the Selection and Use of Essential Medicines which took place in Geneva in January 2010 to consider treatment of the pandemic influenza virus.