Reported rates of child sexual abuse in China fall at the lower end of the range found in Western studies. However, most of the studies were conducted in only one city or province and thus their results may not be generalisable. Acknowledging the infeasibility of recruiting a truly representative sample, we conducted a survey during 2009–10 using a probability sampling procedure to obtain a large and diverse sample of school-aged adolescents from six regions in China. About one in every 13 children had had experience of sexual abuse. Routine screening in medical and social settings is urged. Efforts should be made to ensure wide awareness of this issue.