To study the trend of under 5 years old children mortality and the leading cause of the deaths in China from 1996 to 2000. The data presented in this report were obtained from the national child mortality surveillance network, including 116 counties (cities) throughout China. The target population was all children under 5 years old in the monitored areas whose mothers or fathers had resided in the area for at least one year. The data were collected and reported by health workers at the three-level network. The neonatal mortality rate (NMR), infant mortality rate (IMR) and under 5 years old mortality rate (U(5)MR) in China dropped to 22.8, 32.2, 39.7 per 1,000 live births in 2000, respectively (they were 24.0, 36.0, 45.0 respectively in 1996), which declined 5.0%, 10.6%, 11.8% from 1996 to 2000, respectively. In urban areas, NMR, IMR and U(5)MR dropped to 9.5, 11.8, 13.8 per 1,000 live births in 2000, respectively (they were 12.2, 14.8, 16.9 respectively in 1996), which declined 22.1%, 20.3%, 18.3% from 1996 to 2000, respectively. In rural areas, NMR, IMR and U(5)MR dropped to 25.8, 37.0, 45.7 per 1,000 live births in 2000, respectively (they were 26.7, 40.9, 51.4 respectively in 1996), which declined 3.4%, 9.5%, 11.1% from 1996 to 2000, respectively. There was a steady decline in the U(5)MR due to diarrhea, pneumonia, neural tube defects and drowning in China. In urban/rural areas, the overall decline in NMR, IMR and U(5)MR from 1996 to 2000 was spectacular. Especially the U(5)MR due to avoidable deaths such as pneumonia and diarrhea was dropped markedly in rural areas.