The present study investigated the sensitivity, specificity, and predictive value of a new in vitro test, the Phadiatop, which detects the presence in serum of specific IgE to a balanced mixture of the most frequent inhalant allergens. Ninety-eight children (63 males, 35 females) 2-12 years old (median age = 6), suffering from rhinitis and/or conjunctivitis and/or asthma were studied. Our data show that Phadiatop has an 87% sensitivity, a 100% specificity, a 92% efficiency, a 100% positive predictive value, and an 86% negative predictive value. These results indicate that Phadiatop is very effective in diagnosing atopy (no false positive). However, a negative Phadiatop does not exclude the diagnosis of atopy.