Chronic urticaria is a common skin disorder characterized by spontaneously appearing wheals and flare-type skin reactions, with or without angioedema. Skin lesions usually persist up to 24 hours and patients generally report pruritus and/or burning sensation. According to the current EAACI/GA2LEN/EDF/WAO guidelines, urticaria may be classified as spontaneous, physical and other types of the disease. Spontaneous urticaria in relation to the duration of the process is further divided into acute and chronic spontaneous types. In contrast to physical and other variants of urticaria, in the spontaneous type, lesions usually occur without any obvious stimuli. It has been demonstrated that in about one-third of patients with chronic spontaneous urticaria, positive response to their own serum is being recorded in the autologous serum skin test (ASST). In general, a positive Result:of ASST reflects autoreactivity and may be regarded to be the basis for further investigations in order to characterize the causative factors. Interestingly, patients suffering from chronic spontaneous urticaria with a positive Result:of ASST present with longer duration and more severe course of the disease and higher requirements for antihistamines and/or alternative methods of treatment.