Eating behavior of school-aged children was dominated by street foods. The aim of the present study was to examine the relationship between maternal knowledge of balanced nutritional guidelines and snack food selection by school-aged children during school hours. This also aims to describe each demographic data and level of mother's knowledge. This study conducted a descriptive correlational design. The participants were selected using simple random sampling technique, consisting of 4th and 5th grade elementary school children and their mothers in SDN Tugu 4, Depok City, Indonesia. Demographic data were also taken for each. The instruments used the Food Frequency Questionnaire and questions about the balanced nutritional guidelines. Statistical analysis conducted a univariate (descriptive) and bivariate (relationship) analysis. Bivariate analysis used independent t test and ANOVA test, using (P value < 0.05) to indicate a significant relationship. A total of 118 elementary students and their mothers participated. The results showed that there was no significant relationship between maternal knowledge of balanced nutritional guidelines and snack food behavior by children during school hours (P = 0.108). Level of knowledge of the mothers on balance nutritional guidelines was dominantly moderate (58.4%). Parents no longer became a major factor influencing the child's diet. Peers have more influence on the diet of children this age. This study points to the importance of education on healthy and safe snack foods for school-aged children in collaboration with peers, parents, teachers, and food vendors at school.