Background: Self-efficacy and outcomes expectation are theoretical constructs that explain many changes in health behaviors, such as the practice of pelvic floor exercises (PFE), and they are predictors of adherence. Women undergoing treatment for gynaecological cancer have different degrees of pelvic floor dysfunction that can be prevented with PFE. The success of these kinds of procedures are dependent on adherence to them. There is a lack of self-efficacy instruments in Spanish related to preventive approaches. Objective: to adapt and validate the Scale of Self-efficacy and Outcomes Expectation for the Practice of Pelvic Floor Exercises (EAPEAP) developed in Brazil. Patients and method: Observational, prospective longitudinal and validation study that included translation- back translation and expert peer review. The psychometric properties of the instrument (internal consistency and predictive capacity) were evaluated, applied to 53 Chilean women referred for radiotherapy treatment for gynaecological cancer. Results: The scale shows good internal consistency, with a Cronbach's alpha of 0.932 for the self-efficacy scale for PFE; and alpha of 0.748 for the outcomes expectation scale for PFE. Regarding predictive validity, the self-efficacy scale was able to discriminate between adherence and non-adherence to treatment (p = 0.034), but not the outcomes expectation scale. For all the analyses, a p < 0.05 was considered. Conclusion: the scale of self-efficacy and outcomes expectation for the practice of PFE is linguistically appropriate and psychometrically valid to be applied in Chile.