Objective:To investigate the clinical characteristics of the disease spectrum of pediatric hyper blood immunoglobulin E (IgE).Methods:A total of 498 children with total serum IgE ≥ 5×10 5 IU/L admitted to the Department of Pediatrics, Sun Yat-Sen Memorial Hospital of Sun Yat-Sen University from January 2012 to December 2018 were enrolled.Their clinical data, etiology distribution, clinical manifestations, laboratory results, treatment and outcomes were retrospectively analyzed.According to serum total IgE level, patients were divided into mildly increased IgE group (5×10 5-<10×10 5 IU/L), moderately increased group (10×10 5-<20×10 5 IU/L), and severely increased group (≥20×10 5 IU/L). The distribution of disease types among the 3 groups were compared. Results:(1) Allergic disease (213 cases) was the most common etiology in children with hyper blood IgE, and infectious disease (163 cases), mycoplasma pneumoniae (109 cases) and EB virus (120 cases) were common pathogens.(2) The incidence of allergic diseases (45.0%) and infectious diseases (42.2%) in the mildly increased group was significantly higher than that in the moderately increased group (40.8%, 26.2%, respectively) and the severely increased group(38.9%, 12.2%, respectively) (all P<0.001). The incidence of immune diseases(18.5%), tumors and hematological diseases (5.4%) in the moderately increased group was significantly higher than that of the mildly increased group (4.4%, 2.0%, respectively) (all P<0.001). The incidence of immune diseases (34.4%), tumors and hematological diseases (11.1%) in the severely increased group was significantly higher than that of the mildly increased group(4.4%, 2.0%, respectively) and the moderately increased group (18.5%, 5.4%, respectively) (all P<0.001). (3) The main clinical manifestations were fever (63.5%), respiratory symptoms (53.7%) and lympha-denopathy (53.7%), 47.5% of the children with hyper blood IgE had an increased white blood cell count, and 12.1% of them had an increased eosinophil count.(4) The most common specific allergens were dust mite combination (32.0%), milk (17.0%), and egg white (16.0%). There was no difference in disease distribution among the 3 groups of hyper blood IgE children with positive specific IgE ( P=0.164). Conclusions:Hyper blood IgE in children are most commonly caused by allergic and infectious diseases.The etiological distributions of hyper blood IgE in children at varying severities differ a lot.The higher the total IgE level, the higher the incidence of immunodeficiency disease, rheumatic disease, tumor and hematological disease.