Elevated serum immunoglobulin E(IgE) can be caused by allergies, infections and immune conditions including hyper IgE syndrome (HIES). HIES is a rare primary immunodeficiency disease most commonly characterized by a triad of findings, including increased serum IgE levels, recurrent skin abscesses, and pneumonias leading to pneumatocele formation. The objective of this study was to characterize the clinical profile of patients presenting with increased IgE levels (>or=2000 IU/mL) focusing specifically on HIES. A database search identified 70 patients in the pediatric age range (<or=18 yrs.) between January 1997 and December 2006 who had an IgE level of >or=2000 IU/mL. Charts were abstracted for clinical diagnosis, comorbidities, and laboratory parameters. Data were analyzed using the students t-test, Wilcoxon signed rank test, and univariate/multivariate regression models. Clinical diagnosis in 70 patients with elevated IgE levels were: atopic diseases (n = 54; 77%), parasitic diseases (n = 1; 1.5%), malignancy (n = 2; 3%), and HIES (n = 6; 8%), among other causes. There was a statistically significant association between IgE levels and the severity of eczema (p = 0.009). Ninety percent of the subjects with IgE level >or=2000 IU/mL did not have HIES. There was no correlation between IgE levels and the diagnosis of HIES (p = 0.5). A variety of clinical situations result in an elevated IgE level, with atopy being the most common cause. In the absence of typical clinical features, elevated serum IgE levels are not predictive of HIES.