This study was conducted to evaluate whether forced expiratory volume in 1 second (FEV1) for the diagnosis of bronchial reactivity by means of the free-running exercise test and bronchodilator inhalation, could be appropriately replaced by simple measurements of peak expiratory flow rate (PEFR) in children.We studied 108 referred symptomatic children (due to chronic cough or wheezing) suspected to have asthma aged 5-14y. Forced breathing spirometry and the "Mini-Wright peak flow meter" tests were recorded before and fifteen minutes after the challenge with free- running exercise or bronchodilator (Salbutamol) inhalation, regarding the baseline FEV1 value (FEV1> 80% considered as normal).There was a high correlation between PEFR and FEV1 (in absolute value and percent predicted) measured before and after bronchodilator inhalation test (r = 0.48, P = 0.05) in comparison to the values referred to free- running exercise test (r = 0.26, P = 0.01)."forced breathing spirometry" and "Mini-Wright peak flow" cannot be used interchangeably for diagnosing asthma, and PEFR measurement should remain a procedure for monitoring and following up the patients.