Background: Influenza A(H1N1) is transmitted through the respiratory tract caused pandemics. To understand the epidemic and to apply the appropriate protection measures in the future, this study was conducted aiming to describe some epidemiological characteristics of influenza A(H1N1) in 2009 in Khanh Hoa province. Methods: Description of the epidemiological characteristics based on the available data obtained from current monitoring systems of infectious diseases (as reported cases of influenza, suspected cases of influenza A(H1N1). the epidemic investigation reports) from all public health facilities. Results: There were 2,204 cases and 2 deaths by influenza A(H1N1) in 2009 in Khanh Hoa province. The morbidity per 100,000 population was 189.9. The mortality (deathslcases) was 0.09. The outbreak lasted 8 months (from 6/2009 to 1/2010). 8 of 8 districts detected cases of influenza A(H1N1). The incidence rate was highest in the urban areas. Schools, production facilities, tourism service facilities were much affected by the epidemic. The morbidity per 100,000 students 1 pupils in the secondary schools, basic secondary schools, primary schools and kindergartens was 383.4 - 343.4 - 124.4 - 42.9 respectively. Analysis of 441 Lab. confirmed cases showed that 89.5 percent of cases were under 29 years old, male had higher rate than female. 37 percent of cases were outpatients who were treated at home and were recovery. Conclusion: The influenza A(H1N1) epidemic in 2009 had the high morbidity and mortality. Cases were concentrated among children and adolescents, particularly in the schools and in the urban areas. The authors should strengthen communication and prevention activities for those at risk for influenza before the epidemic season.