From May 1985 to January 1986, a total of 20 418 school children in Beijing municipality and its suburbs were screened for scoliosis with standardized procedures and criteria. The three-stage screening method was used, i.e., physical examination, Moiré-topography and roentgenographic examination. 213 children were found with a curve beyond 10 degrees (1.04%), and 60 beyond 20 degrees (0.29%). The incidence in relation to age and sex were analysed and treatment programme discussed. It is believed that Moiré topography as a secondary screen is of great help to increase the rate of detection and to save X-ray films in mass screening programme.