Allergy to mosquitoes that produces anaphylaxis is very exceptional. We present two observations of anaphylaxis to mosquitoes with good correlation between the clinical history and the immunological indications of which the basophil activation test proved to be effective. The many allergens of mosquitoes are contained in the juices and salivary glands and their molecular weights are between 22 and 95 kD. Specific immunotherapy, which uses whole body extracts of mosquito, gives good results of protection that induces excellent tolerance and has very good efficacy.