BACKGROUND: Few studies have investigated the epidemiology and disease burden of childhood pneumonia in Taiwan, a middle-income country. METHODS: Using Taiwan's National Health Insurance database, we analyzed the annual population-based incidence and mortality rate of hospitalizations due to pneumonia in children under 18 years old from 1997 to 2004 in Taiwan. RESULTS: The average annual incidence of hospitalized pneumonia was 1,240 episodes per 100,000 children in those below 18 years old. For children under 5 years old and for infants, the incidence was 3,965 and 4,984 out of 100,000, respectively. Boys were more likely to be affected than girls (male to female risk ratio 1.27, P < 0.001). The disease occurred most frequently in the spring and least frequently in the autumn (P < 0.001). In children below the age of 5 years old, mortality due to pneumonia was 6.7 per 100,000 per year for children and accounted for 4.2% of the total deaths in this population. CONCLUSIONS: In Taiwan, pneumonia occurs most frequently in the spring, has an annual incidence of hospitalizations of 3,965 episodes per 100,000 children below the age of 5 years old. It accounts for a mortality rate of 6.7 per 100,000 children in that population, four times that of developed countries (1.6-1.8 episodes per 100,000 children-year). (c) 2009 Wiley-Liss, Inc.