Introduction: The Oxford knee and hip scores are assessment tools developed in English language to evaluate the quality of life in patients with knee and hip arthrosis. The purpose of this study was to adapt the scores to Spanish speaking countries and to evaluate its reproducibility and validity.Materials and Methods: Following the guidelines from the literature, the Oxford scores were translated into Spanish. Eighty patients were asked to complete the questionnaire, 40 patients with knee arthrosis and 40 patients with hip arthrosis. They were asked to answer it for a second time within the next 14 days, to evaluate reliability. The Cronbach's (CA) and the intra-class correlation coefficient (ICC) were calculated to determine test-retest reliability and internal consistency. Bland-Altman plot and reliable change index (RCI) were assessed to evaluate measurement error.Results: The Cronbach's was 0.82 and 0.96, for knee and hip respectively. Excellent testretest reliability was seen through an ICC of 0.98 for knee and 0.99 for hip. The Bland-Altman plot showed no systematic differences, and the reliable change index was 3.5% for knee and 3.1% for hip.Discussion: The Spanish version of the Oxford scores for knee and hip proved to be valid and reliable tools for evaluating quality of life in patients with knee and hip arthrosis, and may be used in Spanish speaking countries.Evidence Level: I.