Numerous studies have investigated the importance of low-glycemic-index (GI) breakfast on cognitive performance. However, until recently, none has used rice and noodles, which are staple foods in Indonesia. This pilot study examined the effect of a low-GI breakfast on cognitive ability of anarithmetic task using locally based food approach. This randomized, crossover study involved 64 high school students (32 male and 32 female students) aged 12 to 15 years. They were provided with a low-GI breakfast or placebo with high GI, which were matched by ±10% for energy amount, serving size, and macronutrient composition. The arithmetic ability Uchida-Kraepelin test was performed 2 hours after breakfast. Paired t test was used to analyze the difference between meals on the outcome. Students consuming the low-GI breakfast had higher scores than those on the high-GI breakfast (80.7 ± 15.9 vs 73.7 ± 17.1), a significant difference (P =.008). The low-GI breakfast was beneficial on these scores, suggesting that further investigations are warranted and that locally based food sources with lower GIs at breakfast might be in order. More tests of cognitive ability are needed to ensure findings are valid, with careful consideration on the issues appearing in this study.