Severe acute Respiratory Syndrome (SARS) is an emerging infectious disease. It is caused by a novel SARS-associated coronavirus. According to the epidemiological data, it is highly infectious by intimate contact, respiratory secretion, or direct contact with infectious body fluid. By June 1, 2003, Center for Disease Control Taiwan, R.O.C reported 677 probable SARS cases. Among them, 93.2% (631/677) were more than 20 years old. Only 6.8% (46/677) were under 20 years old. Usually the major hosts of respiratory viruses are children, but evidence up to now shows that SARS is mainly a disease of adults. The data of clinical presentation and epidemiological prevalence in teenage group and children are lacking. Therefore, this project is aimed at the children and teenager among 1 month to eighteen years old. Seroepidemiology of SARS-CoV infection in children would be investigated. Patients who admitted to pediatric wards or visited ER and received blood sampling due to the need of clinical diagnosis/management would be enrolled. After the necessary laboratory examinations were done, the remaining serum would be collected and tested for anti-SARS-CoV IgG by ELISA.