摘要：Objective. It was analyzed the performance of the institutional websites of the national libraries of Mercosur by means of webometrics indicators: size of website, luminosity, visibility and the web impact factor with natural logarithm. Method. It was about a descriptive research with a quantitative approach. Results. The results show that of the 12 countries belonging to his trade bloc, nine have their own websites. As the results webometric the national libraries that main highlights were the Brazil and Chile, being the Brazil is among the top 3 positions in four indicators analyzed and the Chile in three indicators. Still on the results, both countries are the ones with impact factor on the web, classified as high. It was noted that the website of Peru's national library presented low performance into all indicators, being positioned between the last three placed. Conclusion. The use of webometric indicators showed that the websites of these institutions can serve as a source of information, to study their influence, and their impact on the web, which are associated with the information and content offered on the network.
