OBJECTIVE To assess the Na content reported on the labels of processed foods sold in Brazil that are usually consumed as snacks by children and adolescents. METHODS Cross-sectional study that assessed Na content and serving size reporting on processed food labels. METHODS A supermarket that is part of a large chain in Brazil. METHODS All foods available for sale at the study's location and reported in the literature as snacks present in the diets of Brazilian children and adolescents. RESULTS Of the 2945 processed foods, 87 % complied with the reference serving sizes, although variability in reporting was observed in most of the food subgroups. In addition, 21 % of the processed foods had high Na levels (>600 mg/100 g) and 35 % had medium Na levels (>120 and ≤600 mg/100 g). The meats, oils, fats and seeds groups as well as the prepared dishes had higher percentages of foods classified as high Na (81 %, 58 % and 53 %, respectively). CONCLUSIONS Most of the processed foods had high or medium Na content. We emphasize the importance of revising Brazilian nutrition labelling legislation to standardize reference serving sizes to avoid variation. Besides, we point out the potential for reducing Na levels in most processed foods, as evidenced by the variability in Na content within subgroups. Finally, we have identified the need to develop a method to classify Na levels in processed foods with specific parameters for children and adolescents.