Ghrelin is a peptide hormone, which plays an important role in appetite regulation. The effects of exercise on ghrelin plasma concentrations are still not clear, especially in children and adolescents. The aim of this study was to investigate the response of acylated and total ghrelin concentrations to controlled exercise in school-aged children. Thirty-six healthy school-aged children (mean age 12.61 years, SD ± 0.39) underwent a controlled bicycle exercise test. Before and immediately after exercise, blood samples were taken in order to measure plasma ghrelin concentrations. The control group consisted of 24 healthy school-aged children. After controlled short-time exercise, total ghrelin concentrations showed no significant difference, whereas acylated ghrelin concentrations increased significantly (P<0.001) in the study population compared with the control group. Moreover, we found a correlation between the proportional increase of acylated ghrelin and the duration of exercise (P<0.01), and between the proportional increase of acylated ghrelin and maximal performance (P<0.01). Increased levels of acylated ghrelin after exercise could be a physiological response to ensure a sufficient caloric intake after energy consumption in children and adolescents.