EIB (Exercise-Induced Bronchoconstriction) describes the narrowing that accurs in the airway follow a short period of exercise. EIB is found in 8-10% of normal children population as occult bronchospasm during or after physical activities. The mecanisms of EIB are related to rapid ventilation and mouth brathing which cause beat and water loss during breathing leading to bronchoconstriction. Peak Expiratory Flow Rate (PEFR) measured pre and post-exercise in students aged 12-16 years in girl intrmediate school. Any female shows PEFR values reduction 15% after 6 minutes continuous free running considered as asthmatic patient, this give an incidence rate of asthmatic patient of 9% in female students in this age. Treatment of EIB, Zafirlukast treatment gives (85.7%) protection rate. While salbutamol inhalation gives a protection rate 88%. Only 66.6% of girls with EIB give an improvement in PEFR values after sodium cromoglycate treatment. A regular measurement of PEFR in school students appears to be a good indicator of EIB, while inhalation of salbutaol 15 minutes before exercise give a good protection against EIB attacks at least for 4 hours (AU)