Background: National reports indicate that morbidity and mortality from pneumonia among Thai children has decreased dramatically since the turn of the millennia; notwithstanding, pneumonia remains the leading cause of admission and death in Thai children under five years of age.
Objective: To assess the burden and pattern of acute lower respiratory infection in under-fives in Thailand from the health data in 2010.
Material and Method: Information on respiratory infection using the ICD10: J09-J22 was evaluated for the number of OPD visits, admissions, mortality, monthly incidence and co morbidities of the mortality.
Results: 73% of all OPD visits with ALRI were in under-fives: one-fourth of whom required hospitalization. Pneumonia is the leading cause of both admissions and mortality (3.22% and 11.29/100,000 population for this age group, respectively). The highest mortality was in the first year of life (39/100,000). One-fourth of the children (168/639) died within 24 hours of admission and septicemia was the most common co-morbidity.
Conclusion: The respective morbidity and mortality of pneumonia in under-fives fell far short of national targets. To achieve these targets, many key aspects are needed; such as, strengthening the knowledge of healthcare personnel, the cost-effectiveness researches on the causative organism detection and the expanding coverage of the preventable-vaccine.

Keywords: Acute lower respiratory infection, Pneumonia, Children under five