Abstract: Objective To determine the epidemiological characteristics of an influenza A/H1N1 outbreak in an elementary school and evaluate the effect of the control measures. Methods A cross-sectional epidemiological survey was conducted to determine the epidemiological characteristics of this influenza A/H1N1 outbreak. The real-time PCR assay was used to identify the viral nucleic acid. Results Among 1333 students of the school, 13 were infected with an attack rate of 0.98%. The nucleic acid of influenza A/H1N1 virus was detected from 13 of 41 throat swabs collected from the patients. The outbreak started on June 19, 2009, peaked on 22, and ended on 23. The epidemic was confined in class 4, grade 6, with a male to female ratio of 1.6 ∶ 1. The patients were aged between 12 and 14 years, demonstrating such major clinical symptoms as fever, cough and sore throat. No severe or death cases were present. Conclusion This was an outbreak of community-acquired influenza A/H1N1.The combination of home quarantine and hospitalization was key to the control of the outbreak.