Estimates of bullying and bullying victimization rates vary depending on how these rates are measured. The current study used survey methods of the World Health Organisation (WHO) to investigate the prevalence of school bullying among secondary students in Taiwan. We also examined whether results differed between surveys with and without definitions of bullying. Olweus-type global items and the timeframe, response categories, and cut-off point adopted in the WHO's Health Behaviour in School-Aged Children study were used in this study. Surveys were administered to secondary students in Taiwan (grades 7-12), with 3,554 students receiving surveys with a definition of bullying and 793 receiving surveys without a definition of bullying. The following results were obtained: (1) In the survey with bullying defined, the self-reported prevalence rates of bullying, victimization, witness to bullying, and bully/victims were 10.9%, 10.7%, 29.9%, and 5.5% respectively; (2) male students were more involved in school bullying than females; (3) no significant difference in prevalence rates was found between the two survey versions. International bullying prevalence rates, gender differences, and the effects of a bullying definition are discussed.