Summary The autologous-serum skin test (ASST) can cause a wheal-and-flare response in some cases of chronic idiopathic urticaria. We subjected 102 patients affected by chronic idiopathic urticaria to this test and studied some clinical parameters to detect any significant differences between ASST-positive and ASST-negative patients. The only significant difference we noted between the two groups was the incidence of angioedema (P = 0.01). We suggest that the ASST cannot be used alone either to predict the severity of urticaria or to define it as ‘autoimmune’.