To investigate the possible role of allergy in asthma or chronic rhinitis, four groups of tests can be used. The patient's history, which is the best way to determine the severity of the disease and the clinical relevance of the allergens detected by other diagnostic means. Tests which disclose an atopic constitution. The predictive value of the serum level of total IgE is somewhat lessened by 20-30% false positive and false negative results. Phadiatop, introduced in 1986, appears to be a more accurate screening test for respiratory allergy. Tests which disclose the presence of allergen-specific IgE, in the skin (skin tests) or in serum (RAST). Tests which reproduce the allergic disease in the shock organ (conjunctival, nasal and bronchial provocation tests). These tests are used in clinical research rather than in the routine diagnosis of allergy.