Background/Purpose: Rapid diagnosis of influenza was important in the global pandemic influenza A/H1N1 outbreak. The QuickVue Influenza A+B test is one of the most common tests for rapid diagnosis of influenza. We evaluated the sensitivity and specificity of the test in children. Methods: We collected data from 970 patients with influenza-like illness who received rapid influenza antigen tests using the QuickVue Influenza A+B test as well as viral isolation. We compared the results with that of viral isolation and reverse-transcriptase polymerase chain reaction (RT-PCR) assays. Results: Based on viral culture, the QuickVue Influenza A+B test had an overall sensitivity of 0.82 (419/513) and specificity of 0.99 (70/71), with a positive predictive value (PPV) of 0.74 (419/563) and a negative predictive value (NPV) of 0.77 (313/407). The sensitivity of QuickVue was significantly higher in specimens with high viral loads. If the viral loads were less than 10(6), the sensitivity of QuickVue was 0.62, while the sensitivity of QuickVue was 0.88 if the viral loads were higher than 10(6) (p