IL-31 represents a novel cytokine involved in pruritic skin diseases including atopic dermatitis (AD). We, therefore, aimed at investigating IL-31 levels in chronic spontaneous urticaria (CU). We included 46 patients with CU, 26 non-atopic skin healthy subjects as negative and 28 patients with AD as positive controls. IL-31 serum levels were analysed using commercial ELISA kit. IL-31 serum levels were higher in patients with CU compared to healthy controls (P < 0.001), but lower compared to patients with AD (P < 0.001). There was no difference in IL-31 serum levels in autologous serum skin test positive or negative CU patients and patients with infectious trigger factors including helicobacter pylori infection. IL-31 serum levels may play a role in the pathophysiology of CU. This is supported by the finding that not all patients with CU respond to antihistamine treatment but to the treatment with immunosuppressive drugs.