Asthma is a chronic respiratory disease. Patients with asthma often require hospitalization or use reliever medication in acute asthma periods. Asthma in older children are rare than small children. However, the numbers of children over 6 years of age hospitalized due to acute asthma seem do not decrease. the authors conduct a study in order to seek the numbers of risk factors for hospitalization of children with asthma aged between 6-15 years. This was a series of cases of asthma during the one year (9/2011-8/2012) at the Department of Allergy and. Immunology, National Hospital of Pediatrics. The results showed that there were 106 children with acute asthma admitted to hospital in one year. The highest proportion of children with acute asthma admitted to hospital in October, when seasonal changing. Children usually had to increase the number of white blood cells (72.6 percent) and neutrophils (66 percent ). 53 percent of children had Rhinovirus infection. Nearly 50 percent of them were reduced FEV1. 73.6 percent of children were uncontrolled or partially controlled asthma. Conclusion: There are many factors alone or in combination to contribute to the onset of acute asthma in children and the prevention of these factors may reduce the risk of acute asthma in children.