OBJECTIVES: To develop and validate a questionnaire for completion by patients having shoulder (other than stabilisation) operations. METHODS: A Patient Reported Outcome (PRO) measure was created following review of available PROs and after interviewing 20 patients attending an outpatient’s shoulder clinic. The drafted 22-item PRO was initially tested in a pilot study with a new set of 20 patients. The original PRO was modified after the pilot study which was then tested on two further groups of patients resulting in the final 12-item PRO.  A prospective study of 111 patients was undertaken before operation and at follow-up six months later.  Each patient completed the new questionnaire and the SF36.  Some filled in the Stanford Health Assessment Questionnaire (HAQ).  An orthopaedic surgeon assessed the Constant clinical assessment score. RESULTS: The single score derived from the developed questionnaire had a high internal consistency (Cronbach’s alpha of 0.89 pre-operative and 0.92 post-operative).  Reproducibility, examined by test-retest reliability, was found to be satisfactory. The validity of the questionnaire was established by obtaining significant correlations in the expected direction with the Constant clinical assessment score and the relevant scales of the SF36 and the HAQ. Sensitivity to change was assessed by analysing the differences between the preoperative scores and those at follow-up. Changes in scores were compared with the patients’ responses to postoperative questions about their condition. The standardised effect size for the new questionnaire compared favourably with that for the SF36 and the HAQ. The new questionnaire was the most efficient in distinguishing patients who said that their shoulder was much better from all other patients. CONCLUSIONS: The Oxford Shoulder Score provides a measure of outcome for shoulder operations which is short, practical, reliable, valid and sensitive to clinically important changes.