目的：通过对浙江省2000~2009年5岁以下儿童的死亡率和死亡原因分析，掌握浙江省5岁以下儿童死亡率的变化趋势，提出降低儿童死亡率的对策。方法：采用分层随机整群抽样方法抽取浙江省30个市/县/区，抽样区内所有5岁以下儿童为研究对象，采用描述性统计和卡方检验，从年龄和户籍等多角度分析儿童的死因及死亡率。结果：浙江省5岁以下儿童死亡率呈现下降的趋势，从2000年的14.83‰ 降到2009年的 9.49‰。2009年农村5岁以下儿童死亡率高于城市（9.14‰ vs 6.50‰，P<0.01），流动人口5岁以下儿童死亡率高于本地人口（12.12‰ vs 6.42‰，P<0.01）。早产和低出生体重是2009年5岁以下儿童的首位死因，其中婴儿组前三位死因分别为早产/低出生体重、先天性心脏病和出生窒息，幼儿组前三位死因分别为溺水、交通意外和意外跌落。结论：2009年浙江省5岁以下儿童死亡率在城乡之间、本地和流动人口之间存在差异。不同年龄组儿童间主要死亡原因不同，为了降低婴儿期儿童死亡率，重点在预防早产、低出生体重和先天异常，对幼儿期儿童，要努力减少意外伤害的发生。

OBJECTIVE: To study the underfive mortality rate and the causes of death in Zhejiang Province between 2000 and 2009 in order to provide a basis for reducing the mortality rate in the region. METHODS: By stratified random cluster sampling, all the children under 5 years old from 30 sampling areas of Zhejiang Province between 2000 and 2009 were enrolled. The under-five mortality rate and the leading causes of death were investigated by descriptive analysis and Chi-square test. RESULTS: The under-five mortality rate demonstrated a decreased trend in Zhejiang Province between 2000 and 2009, with the under-five mortality rate of 14.83‰ in 2000 compared to 9.49‰ in 2009. In 2009, the under-five mortality rate in rural regions was significantly higher than that in urban regions (9.14‰ vs 6.50‰; P<0.01). Compared with the resident population, there were an increased under-five mortality rate in floating population (12.12‰ vs 6.42‰; P<0.01). Preterm delivery/low birth weight was the top death cause in children under 5 years old. The top three causes of death in infants less than 1 year old were preterm delivery/low birth weight, congenital heart disease and birth asphyxia compared to drowning, traffic accident and falling in children aged 1-4 years. CONCLUSIONS: There are differences in the under-five mortality rate between rural and urban children as well as between the floating and resident population in 2009. The leading causes of death in different age groups are different. It is essential to reduce the mortality rate by preventing preterm delivery, low birth weight and congenital malformations to infants and preventing accidental injuries to children aged 1-4 years.