Background: The etiology of urticaria is recognized only in a minority of cases. Allergies to a wide variety of agents have been suspected, as well as hyper reactivity to food additives or drugs. Recently, autoimmune reaction to immunoglobulin E (IgE) and later to high-affinity IgE receptors on mast cells has been reported. The aim of this study was to show elevated serum IgE levels in the patients with chronic idiopathic urticaria (CIU) so that the underlying disease and the cause of CIU may be atopic condition or an occult disease with raised serum IgE. Method: Altogether, 57 patients (30 women and 27 men, with an age range from 14 to 75 years ; mean age of 35.86 years), who suffered from chronic urticaria with a duration of 3 months to 8 years were included in this study and serum IgE level was assessed. Result: Thirty three patients had elevated serum IgE levels. The range of IgE levels were 114-3280 U (geometric mean greater than 100 ku/l) and mean IgE level was 411.39 U. Conclusion: Although the causes of CIU are often not clear, at least one causes of CIU may be atopy or other diseases that may be hidden and show elevated serum IgE. The patients present with CIU along with elevated serum IgE, should be investigated for atopy or other diseases that may be associated with elevated serum IgE.