Chronic urticaria is considered to be a heterogeneous disease, which can be divided into several subclasses. The authors investigated 126 patients suffering from chronic urticaria with 41 of unknown origin. The aim of the present study was to work out a strategy for the complete investigation of patients with chronic urticaria. The findings of the immunological study modified the results obtained by medical assessment of the 126 chronic urticaria cases, diminished the number of the patient with chronic urticaria unknown etiology.