Chronic idiopathic urticaria (CIU) is not uncommon, yet there is little information about the clinical features of CIU patients in Taiwan. The purpose of this study was to investigate the clinical features of CIU in Taiwan. Methods: Patients with CIU were collected consecutively from the Urticaria Special Clinic in a medical center in northern Taiwan from December 2005 to May 2006. Clinical features and laboratory findings were studied. We also evaluated the therapeutic response of CIU patients with second-generation H1 receptor antagonist monotherapy for 6 weeks. Results: A total of 62 CIU patients were investigated. The female to male ratio was 2.1:1 with a mean age of 31.8 years. The mean duration of the disease was 25.7 months (1.5-180 months). The most common aggravating factor was weather (79.7%), especially hot weather (50.8%). Fifty percent of the patients had atopy, and 37.3% of patients had positive autologous serum skin test. Besides, 61.3% of patients had at least one serum specific IgE antibody to the 18 common allergens examined. Finally, 60.7% of patients responded well to second-generation H1 receptor antagonist. Non-responders tended to have atopy (p = 0.0471), especially allergic rhinitis (p = 0.0107). Conclusions: This study provided an overview of CIU patients in a medical center in northern Taiwan. We found that atopy did not influence the severity or durtation of CIU. Nevertheless, atopy was associated with a poor therapeutic response of second-generation antihistamine. A survey of personal atopy history, especially allergic rhinitis, is important for management of CIU patients in Taiwan.