Objectives: The Performance Enhancement Attitude Scale (PEAS; Petróczi & Aidman, 2009) is an extensively used questionnaire to assess doping attitudes among adult and adolescent athletes. To date, however, there is limited evidence to support the structure of the PEAS with either adult or adolescent athletes. The aim of this paper was to assess the factor structure of the PEAS with adult and adolescent athletes. Design: Cross-sectional. Methods: One thousand, one-hundred and fifty-four athletes, who were aged between 12 and 68 years (M age = 21.76 years, SD = 7.68) completed the PEAS in the presence of a research assistant. We subjected the data to Confirmatory Factor Analysis. Results: The original 17-item PEAS displayed a poor model among the overall sample, and with the sub-samples of adult and adolescent athletes. The 11-item, 8-item, and 6-item versions of the PEAS, which were used in previous studies, provided a better fit than the original 17-item PEAS. The 8-item version of the PEAS demonstrated the best fit for adults, but no model exhibited a good fit with adolescent athletes. Conclusions: Scholars could consider using the 8-item version of the PEAS with adults. Our data, however, infers that researchers should use the PEAS with caution to assess doping attitudes among adolescent athletes, due to the poor model fit of all versions tested. The accurate assessment of attitudes towards doping among adolescent athletes requires questionnaires specifically designed for this population, and grounded in an appropriate theoretical framework.