This study was conducted at the outpatient pulmonary clinic, Department of pediatric, Cairo University. It included forty children with mild and moderate asthma, Patients are subjected to complete history taking and clinical examination, pulmonary function test by peak expiratory flow meter, some laboratory investigation as complete blood picture, serum level of immunoglobulin E and Serum leptin level. The study revealed that there is significant increase in serum leptin level in asthmatic children more than control group, and that the level of serum leptin is the most predictive test for asthma.