- Introduction Patch testing is performed to diagnose allergic contact dermatitis to avoid exposure to the revealed contact allergens. Nevertheless, patch testing is not routinely performed in the evaluation of patients with chronic idiopathic (spontaneous) urticaria (CIU). The objective of this study was to determine the frequency of sensitization to patch test allergens in severe CIU and assess a role of the allergen avoidance in CIU remission. Methods The cases of patients with severe CIU were retrospectively studied. The patients were patch tested using T.R.U.E. TEST. Three groups were studied: CIU with positive patch test group; CIU with negative patch test group and control group, which included the cases of not patch-tested patients with CIU. The groups were followed up monthly to assess changes in Chronic Urticaria Severity Score (CUSS) after allergen avoidance. Results Fortythree subjects with severe CIU were patch tested. Nickel sulphate was positive in 4 (9.3%) cases, potassium dichromate in 2 (4.7%) cases, cobalt, balsam of Peru, paraphenylene diamine, fragrance mix and epoxy resin were positive in 1 (2.3%) case. Their baseline CUSS (5.4 ± 0.5) improved significantly after 1 month of allergen avoidance (3.2 ± 1.1; P < 0.001); but similar improvement of CUSS (5.3 ± 0.5) was seen in 34 patients with CIU with negative patch test (3.2 ± 1.3; P < 0.001) and in 49 patients with CIU of control group (5.2 ± 0.4 to 3.4 ± 1.3; P < 0 < 0.001) after 1 month. Conclusions: There is no relationship between avoidance of contact allergens and the course of CIU.