Typical cases of pollen allergen (hayfever, allergic asthma), together with isolated non-respiratory "equivalent" manifestations (urticaria, eye conditions, headache, etc.), are easy to detect on the basis of skin tests and the clinical history. Such manifestations may also occur in "false pollen allergy", related in most instances by atmospheric moulds (Dematiaceae), sometimes by house dust or dermatophytes (Candida Albicans, Trichophyton sp), by food or by a bacterial infection or allergy. A combination of pollen allergy and false pollen allergy is common. In cases of false pollen allergy the proportion of negative skin reactions would appear to worsen with the repeated use of prolonged action corticosteroid injections, given on a preventive basis. Similarly, these disorders, initially seasonal, change to more chronic manifestations throughout the year. Desensitization with aqueous extracts of allergens ensured the most complete protection against the causes of pollen allergy and false pollen allergy. Allergen extracts percipitated with alun (semi-retard extracts), more effective than tyrosine adsorbates (Pollinex) have the advantage of offering more rapid treatment without the risk of dangerous reactions. The best therapeutic results have obtained over the course of the last ten years, by the authors, combining on each occasion a semi-retard allergen with an aqueous allergen, thereby acquiring the benefit of the adjuvant effect of the first, in a course of ten to fifteen injections per year. Non specific therapy (antihistamines, cromoglycate, theophylline, etc.) retains all of its symptomatic indications. Oral corticosteroid therapy is better metabolized in the organism and has less of a disturbing effect on the circadian rhythm of cortisol, and is hence to be preferred to injections of delyaed action corticosteroid suspensions.