ObJECTIvE: This article describes the development and validation of the osteoporosis treatment questionnaire (OSTREq), which is a physician-reported outcome tool aiming to evaluate physicians' criteria in the choice of osteoporosis treatment. DESIgN: The questionnaire -named OSTREq-consisting of 17 questions that were divided into eight sections "health Care System", "patients' preference in administration routes", "Usage, Cost", "Severity of Disease", "Treatment Efficacy", "Safety profile", "pharmaceutical Industry", affecting the decision and overall execution of a therapeutic approach, was developed by an expert panel and was later officially translated into English. In the second phase, orthopedic surgeons were asked to complete OSTREq. Six indirect methods to evaluate validity were adopted: exploratory factor analysis, confirmatory factor analysis, subscale validity, known group validity, floor or ceiling effects, interpretability. To assess the reliability of the questionnaire, internal consistency validity as well as test-retest and parallel forms were calculated. RESUlTS: One hundred seventy-two orthopedic surgeons were interviewed with an average period of experience in clinical practice of 10.5 years (SD ±8.9 years). The factors "Severity of Disease" and "Treatment Efficacy" were the most important in the choice of osteoporosis treatment, while the factor "pharmaceutical Industry" had the least impact. The methodology of validation proved that the questionnaire possesses construct validity, discriminate ability, reliability, and sensitivity to change. CONClUSIONS: OSTREq represents a comprehensive and focused tool that, for the first time, assesses physicians' criteria in the choice of osteoporosis treatment. This tool could assist health care systems and pharmaceutical companies to be aware which parameters drive physicians' preferences regarding osteoporosis treatment.