In the environment of managed care, children with allergic diseases are increasingly likely to be evaluated by nonallergist physicians. While the presumptive diagnosis of an allergic disease can often be suspected on clinical grounds, signs and symptoms are not reliable for establishing a definitive diagnosis or for deciding on management options. This article discusses the use of immunoglobulin E antibody tests to classify children with allergic symptoms. The information is intended for pathologists who offer consultative laboratory services to nonallergist physicians. Emphasis is placed on defining the minimum number of tests necessary to identify allergic children at different ages.