Background and Objective: User satisfaction is an important indicator of primary health care (PHC) services. The Net Promoter Score (NPS), originally proposed by Reichheld in 2003, has been adapted for use in health services in several countries around the world. The Brazilian Institute of Geography and Statistics (IBGE) used it for the first time to evaluate primary health care services in the Unified Health System (SUS). Methods: IBGE used the reduced version for child users of the Primary Care Assessment Tool (PCAT) created by Starfield and Shi and validated by the Brazilian Ministry of Health and included NPS. Random cluster sample (n = 4,973 children) allowed comparing the overall PCAT score with NPS. NPS is a single metric that quantifies the response to the question: How likely are you to recommend this service? Three categories are identified and classified as ‘promoters’ (those who would definitely recommend and use the service again), ‘passives’ (who are broadly happy, but would not actively promote the service) and ‘detractors’ (who actively discourage others to experience the service). The Results of calculating this indicator ranges from -100 to +100. NPS can be classified as: (i) critical zone (-100 to 0), (ii) improvement zone, between 1 and 50; (iii) quality zone, between 51 and 75; (iv) excellence zone, between, 76 and 100. Results: For all regions of Brazil, the NPS estimated by the IBGE is in the improvement zone, with important intra-regional differences in the Brazilian states. The higher the PCAT score, the greater the proportion of promoters in the NPS. Conclusions: Due to its simplicity of implementation in PHC services in Brazil, NPS could be incorporated in assessing user satisfaction.