Brazil is the most populous country in the world with a public, universal, and entirely free health care system. The Brazilian Sistema Unico de Saude - SUS, created in 1988 with the principles of universality, equity and integrated care, provides primary, secondary and tertiary health care. In 2006, SUS established Estrategia Saude da Familia (Family Health Strategy-FHS) as the primary health care (PHC) strategy at the municipality level. This strategy provides a broad range of primary health care services delivered by a multidisciplinary team comprised of physician, nurse, dentist, nursing assistant, dental assistant, and community health workers. Each team is responsible for about 4,000 people. The Family Health Team (FHT) professionals are supposed to work under the aegis of primary health care principles; providing basic health care, promoting health activities and preventing diseases, as well as referring those in need to other levels of care. As of 2017, there are 41,000 FHTs, comprised of about 700,000 professionals, who care for 124 million people in the country, present in 95% of Brazil’s municipalities (63.7% of the population). Considering the need for institutionalization of evaluation processes of the FHS, as well as the need to establish quality standards in public health services in the PHC system, the National Program for Access and Quality Improvement in Primary Care (Programa Nacional de Melhoria do Acesso e da Qualidade da Atencao Basica - PMAQ) was implemented in 2011. We are presently on the 3rd cycle of this program, which includes a multicenter FHT external evaluation in 2017.This is an investigation, with application of a single national survey. The questionnaires were organized into 3 major modules: 1. infrastructure conditions; 2. teams work process/care organization; 3. users satisfaction and perception of services. The implementation of such research proccess is complex and needs a series of organization strategies. We will present the methodology, as well as describe the advantages, disdvantages and chalenges of such endevour from the perspective of Universidade Federal do Rio Grande do Norte (UFRN), one of the 7 institutions performing the study. A total of 3,856 teams were evaluated in 2017. For the fieldwork of Rio Grande do Norte-RN and Ceara-CE (two Brazilian states), 90 interviewers, 18 field supervisors and State coordenators were hired and trained. Tablets were used to conduct the research and the questionnaires were sent via wi-fi to a data center. A gerential computational system was developed in order to facilitate the follow up of such wide research. Several chalenges were faced during the implementaion of the reseach: logistical pactuations (setting the best routs and pactuating with municipalities the dates of the data collection), interviewers locomotion between municipalities (distances, geographical barriers, lack of official transport), change of interviewers during the field, financial and wi-fi limitations, among others. Nevertheless, the implementation of a such survey guarantees important information for FHT planning activities and public policy implementation and survailance. The understanding of those chanleges, as well as the advantages and disadvantages of this type of evaluation may help the organization of other similar researches.