Background: Asthma is a complex disease that is characterized by airway inflammation and bronchial hyperresponsiveness and results from an interaction of inherited and environmental factors. Large-scale genome screens have identified several chromosomes linked to the diagnosis of asthma. The IL12 gene is a potential candidate for asthma because of its role in regulating TH1/TH2 response and it is also important in cell-mediated immunity. he main purpose of this case-control study was to detect assosciation of single nucleotide polymorphism in IL12 A and B with bronchial asthma in Egyptian children and its assosciation with asthma severity, family history of asthma, presence of other atopic conditions, total eosinophilic count and total serum IgE. Methods: Forty asthmatic children were included in the present cross-sectional case-control observational study with age from 6 month to 6 years. All were referred to the allergy clinic, new children’s hospital, Cairo University for management and follow up. Forty age and sex matched healthy children with no history of current or previous atopic and/or upper or lower chronic airway diseases were included as controls. Patients and controls included were subjected to detailed history taking, thorough clinical examination, measurement of absolute eosinophilic count, total serum IgE and detection of SNP in IL 12A rs2243115, rs568408 and IL 12 B rs3212227 by using restriction enzyme-based RFLP genotyping was performed Results: Our study showed no assosciation between SNP in IL 12A rs2243115, rs568408 and IL 12 B rs3212227 and asthma (p-value= 0.626, 1.00 and 0.230) respectively or asthma severity classification whether intermitent, mild persistent or moderate presisetent (p-value=1.000, 0.804 and 0.938) respectively. Also there was no significant statistical difference in IL12 A rs2243115, rs568408 and IL12 B rs3212227 polymorphisms in relation to other atopic conditions (p-value= 0.716, 0.567and 0.559) respectively. No significant difference was noted in IL12 A rs2243115, rs568408 and IL12 B rs3212227 polymorphism in relation to positive family history (p-value= 0.455, 0.385) respectively. No statistical relation was found between these polymorphisms and the absolute eosinophilic count (p-value=0.116, 0.748 and 0.310), respectively. No statistical relation has been found between IL12 A rs2243115, rs568408 and IL12 B rs3212227 polymorphism and the absolute eosinophilic count (p-value=0.116, 0.748 and 0.310) respectively.Conclusion: Single nucleotide polymorphism in IL12 A and B was not assosciated with bronchial asthma in Egyptian children.