This study surveys the diagnostic agreement between two different analytic systems for the measurement of serum specific IgE (sLgE), Immulite 2000 (IML) and ImmunoCap (CAP), with clinic evaluation and in vivo test. Our sample is represented by 33 adults (27 females and 6 males), with suspect of immediate allergic disease and suspect of sensitization to at least one allergen of the study panel (18 allergens: inhalant, alimentary and professional). All patients have been subjected to Skin Prick Test (SPT) for all the studied allergens, therefore sIgE measurement with IML and CAP systems has been executed (twice for each method) only for the allergens which resulted positive to the diagnostic suspect and to SPT, and for an equal number of allergens chosen by bound randomisation. In vitro methods (IML and CAP), evaluated by K Cohen statistics, give good diagnostic agreement. In the same way, the diagnostic agreement of the used analytic systems both with clinical suspect and with in vivo test is satisfying, with higher K values for IML.