Using the WHO model list of essential medicines to update a national essential medicines list Since 1977, WHO has been working with countries to design the package of essential medicines as an integral component of treatment within the continuum of care, developing and disseminating the Model List of Essential Medicines (Model List). WHO is committed to supporting Member States in sharing best practices in selecting essential medicines, and in developing processes for the selection of medicines for national essential medicines lists (national EMLs, or NEMLs) consistent with the evidence-based methods used for updating the WHO Model List.