Inconsistent reports of the prevalence of risk perception accuracy may be related to the use of different classification strategies. The purpose of this study was to compare two approaches for assessing the accuracy of women's breast cancer risk perceptions. A telephone survey was conducted with an age-stratified random sample of British Columbian women 20-79 years of age without a breast cancer diagnosis (n = 761). A comparison of two methods employed to determine perception accuracy revealed substantial differences between the methods with regard to the classification of women as under- and over-estimators. The study highlights the need for researchers to consider the method used to determine the accuracy of risk perceptions and the implications of using different strategies to assess risk perception accuracy when such information is used in research or to guide interventions.