PhadiatopTM is a new in vitro test used for screening patients with allergic respiratory diseases. This test, based on the RAST procedure, is performed with a paper disc to which a balanced mixture of relevant inhalant allergens has been coupled. One hundred and one adults ranging in age from 18 years to 73 years and 38 children (4 months to 15 years) were studied. We found a good correlation between this new test and total IgE (adults: 74.3 p. 100, children: 68.4 p.100), specific IgE (adults: 91.1 p. 100, children: 100 p. 100) and skin test (adults: 79.2 p. 100, children: 97.1 p. 100). There was a high correlation between clinical atopy assessment and the result of PhadiatopTM; its efficiency was 83 p. 100 in adults and 97 p. 100 in children.