Fractional exhaled nitric oxide (FeNO) is a noninvasive marker of inflammation, used for monitoring asthma. The aim of this study was to compare FeNO, asthma control test (ACT), and lung function test (spirometry) in children aged 8-15 years. This observational, cross-sectional study was performed on76 asthmatic children (age, 8-15 years), who were referred to the Department of Immunology and Allergy, Children’s Medical Center, Tehran, Iran during 2012-2013. Patients were matched for sex and age. The recruited patients were selected via consecutive sampling. FeNO was measured with a portable electrochemical analyzer and forced spirometry was performed according to the American Thoracic Society (ATS) guidelines. The ACT questionnaire was used and completed for all the patients. The mean FeNO was 28.5±29.1 ppb, and the mean ACT score was 19.8±3.6. FeNO was significantly correlated with forced expiratory volume (FEV1) (r, 0.232; p=0.049) or 25-75% maximum expiratory flow (MEF 25-75) (r, -0.304; p=0.009). FeNO showed no significant correlation with ACT score or FEV1/forced vital capacity (FVC) (p>0.05). Additionally, there was no significant correlation between FeNO and changes in FEV1 and MEF 25-75% before and after the administration of bronchodilators (p>0.05). To improve asthma control, childhood ACT, FeNO, and spirometric tests can be used as complementary tools in clinical practice to detect children with poorly controlled asthma.