We assessed the test characteristics of 2 influenza antigen tests, a rapid immunoassay and a direct fluorescence antibody (DFA) assay, in detecting pandemic influenza A (H1N1) in children up to 18 years of age, using polymerase chain reaction as the standard. The sensitivities of BinaxNOW (59.6%) and direct fluorescence antibody (57.3%) were similar. The specificity of each test was >99%.