Specific desensitization is one of the most widely used treatments in children and adolescents. It was introduced 65 years ago, but its scientific foundations have only been established during the last 10 years. At the beginning of this decade, the development of standardized allergens and improvements in the technique of administration inclined us to consider that desensitization was a promising technique. In 1988, however, these hopes must be mitigated for several reasons. Desensitization is effective when used appropriately and with a strict methodology, but the advent of potent allergens has increased its risks. Desensitization is now criticised, sometimes severely, on account of its efficacy/safety ratio and its duration. It seems that more than one-half of patients allergic to vespid venom can discontinue desensitization after 3 years, but the treatment lasts much longer in other allergies, and some patients sensitized to perennial allergens should be injected for life, which raises the problem of the cost of desensitization. At the moment, this method is regarded as indispensable to prevent allergy to Hymenoptera, useful in patients with moderate asthma due to allergy to house mites, and to be envisaged in some patients allergic to pollens or to cats. If desensitization has a future, it will reside in allergens at least equal in quality to those now available but safer, and also perhaps in techniques using monoclonal or anti-idiotype antibodies.