Objective To assess the dental caries prevalence of children in Yinchuan.Methods The 3-, 5-, 12-, 15-year- old children were chosed from nursery, primary and middle schools of Yinchuan in 1990, 1996 and 2001. The surveywas carried out by five senior dentists from stomatologic hospital of Yinchuan according WHO criteria. DMFT, DMFS and the ratio of tooth filled were counted.Results From 1990 to 2001, the prevalence of dental caries of 3-, 5-, 12-year-old children was degression (P