Background.  Asthma  is one  of the most common respiratory disorders in children and is charecterized by distal airway inflammation and hyperresponsiveness. This disease challenges human health because of its increasing prevalence,  severity,  morbidity,  and the lack of a proper and complete cure.  Complement proteins are responsible for many pathophysiological features of asthma, including inflammatory cell infiltration, mucus secretion, increase  in vascular permeability, and smooth muscle cell contraction. Objective. To assess the serum levels of complement factors C3 and C4 in Egyptian asthmatic children. Patients and methods. This case controlled study comprised of 60 Egyptian children with the diagnosis of bronchial asthma  and 30 age-and sex-matched healthy controls.It  was conducted in Al-Azhar University Hospitals, from January 2016 to Septemper  2016. All candidates were subjected to athorough clinical study, complete blood counts, absolute eosinophilic count and serum complements (C3, C4). Results. Serum C3 levels were significantly higher in asthmatics when compared to controls (179.08 ± 44.04 mg/dlvs123.70 ± 22.17mg/dl respectively, p < 0.01). Also, C4 levels were higher compared to controls (42.7±15.58 mg/dl vs 27.3 ± 6.89 mg/dl respectively, p < 0.001). There was a significant positive correlation between severity of asthma and serum C3 and serum C4. Conclusions. Serum levels of C3 and C4  are elevated in children with bronchial asthma, with a positive correlation betweentheir levels  and severity of asthma.