Objective: The objective of this laboratory-based pilot study was to test the effects of consuming, compared with omitting, breakfast across 6 cognitive domains and on levels of perceived energy and well-being. Methods: In a crossover design, 21 boys and girls, 8 to 10 years of age, were assessed once a week for 2 weeks. On each test day, subjects performed a series of 8 computerized cognitive performance tasks using the CogState© software program throughout the morning, but they either consumed or did not consume breakfast. In addition, subjects repeatedly rated their perceived energy level, fatigue, overall well-being, and cheerfulness using a 100-mm Visual Analog Scale. Results: Results showed no significant main effect of breakfast condition (p > .17) or breakfast condition-by-time interaction (p > .09) for any of the cognitive performance tasks. On the day when children consumed breakfast, they felt significantly more cheerful (p = .02) and indicated to have more energy (p = .04) than on the day when they skipped breakfast. Conclusion: Among children who regularly consume breakfast, skipping breakfast once significantly decreased their perceived level of energy and cheerfulness, but it did not affect their cognitive performance throughout the morning. More experimental studies are needed to assess the effects of different types of breakfast on cognitive performance in children over a prolonged period of time while controlling for familial factors that may affect cognitive performance in children.