Thaisy Mendes Porto,1 Daniele Caferatti Machado,1 Rafael Olívio Martins,2 Dayani Galato,3 Anna Paula Piovezan31Course of Pharmacy, 2Course of Medicine, 3Post-Graduation in Health Sciences, University of Southern Santa Catarina, Tubarão, Santa Catarina, BrazilBackground: Locus of pain control (LPC) is characterized by the behavior of people coping with their health problems, as a result of their own actions (internal control) or external factors or other people (external control). This parameter can be associated with medication adherence, in addition to other psychosocial factors that may also influence this behavior. This study was performed to investigate the influence of the LPC on medication adherence in patients undergoing an orthopedic procedure. Subjects and methods: We conducted a prospective cohort study on patients who attended an orthopedic clinic for arthroscopy treatment. The patients’ LPC and pain intensity data were obtained on the day of admission through the use of the LPC scale and the visual analog scale (VAS), respectively, both being validated tools. After arthroscopic surgery, the patients received drug prescriptions and were reassessed after 15 days regarding treatment adherence, using the Morisky test. A P-value 0.01). Conclusion: The results showed that among patients who underwent an orthopedic procedure, there was a higher adherence rate to prescribed medication in the external LPC group compared with the internal LPC group.Keywords: behavior, locus of control, compliance