ABSTRACT Objective: To describe the prevalence of underweight and exclusive breastfeeding (EBF) in children aged zero to six months followed by Primary Care in Brazil in 2017, identifying their spatial distribution. Methods: This was an observational, descriptive and ecological study based on data analysis of the Food and Nutrition Surveillance System. The distribution of records obtained was compared to the population estimates of the Brazilian Institute of Geography and Statistics (IBGE). In order to evaluate the EBF, Primary Health Care teams used food ingestion from the previous day. As for underweight, we used: Length-for-age (L/A), Weight-for-age (W/A) and BMI-for-age (BMI/A), according to World Health Organization (WHO) references. Confidence Intervals were calculated 95% (95%CI) for prevalences obtained, being plotted on maps by Federation Unit. Results: Data were obtained from 88.7 and 32.2% of Brazilian municipalities regarding anthropometry and food consumption, corresponding to 167,393 and 66,136 children, respectively. Compared to population distribution, the number of records was underestimated in the North and Northeast for anthropometry/consumption, with distinct proportions in the South for anthropometry and Southeast for consumption. The prevalences found were: EBF - 56.6% (95%CI 56.2-56.9); under L/A - 10.6% (95%CI 10.5-10.8); under W/A - 9.0% (95%CI 8.9-9.1); and under BMI/A - 5.8% (95%CI 5.7-6.0). Conclusions: The estimate of EBF in Brazil was similar to previous studies, but food consumption data still have low coverage, compromising the estimate in some locations. Regarding anthropometry, high rates of low L/A, W/A and BMI/A stood out in some states, considerably above the previous national estimate.