A case of chronic urticaria in a child 6 years old is described. The strong skin reactivity upon intradermal injection of autologous serum suggested an autoreactive pathogenesis; however, patient’s serum was unable to induce histamine release from basophils in-vitro, indicating the presence of a histamine-releasing factor specific
for mast cells, and possibly other than an anti-FcεRI or anti-IgE antibody. Intradermal test with autologous serum may be useful in revealing the autoreactive nature of chronic urticaria and can avoid a frustrating search for other causes of the disease. In children presenting with chronic or recurrent urticaria the diagnostic workup should
include the autologous serum skin test.

Key words: autologous serum skin test, childhood, chronic urticaria.