In general population about 15-20% of subjects have suffered from one episode of urticaria-angioedema syndrome in their life. The etiology of his condition is various and multifactorial. In children the principal cause of acute urticaria is infection, while physical factors are the main agents of chronic urticaria. All those conditions which lack an etiology are named chronic idiopathic urticaria, but in reality a considerable number of these patients is affected by a chronic autoimmune urticaria. For this reason, screening out the most frequent causes of chronic urticaria, it's useful to know when it's possible to apply specific diagnostic tests for this condition and which therapies are employable.