Abstract
This paper presents the analysis of the origin of 391 active ingredients (AIs) of the 9th list of essential medicines in Ecuador, using the system proposed by Newman and Cragg with certain modifications. The AIs of natural origin represent 54.2% of the list and have greater importance in the categories H, R and B of the Anatomical, Therapeutic and Chemical classification system for pharmacological substances and medicines. In addition, the influence of natural products was analyzed in the categories with the highest amount of IAs J, L and N, as well as in category C, which is associated with the main cause of death in Ecuador.