OBJECTIVES: Health related quality of life (HRQoL) is an important issue to evaluate outcomes after health interventions. The aim of this study was to study construct validity and responsiveness of the OsteoArthritis of Hip and Knee Quality of Life questionnaire (OAKHQOL), a disease-specific HRQoL for osteoarthritis of the lower limb. METHODS: OAKHQOL is a self administered questionnaire and has 43 items and five dimensions: physical activities (16), pain (4), mental health (13), social support (4) and social functioning (3). There are 3 independent items about relationships, sexual activities and professional life. The score range from 0 (worst) to 100 (best health). Patients were recruited patients from the waiting list to undergo joint replacement. The internal consistency was measured by Cronbach´s alpha (771 patients). The test-retest reliability (413 stable patients who fulfilled the questionnaire two times) was measured by Intraclass correlation coefficient (ICC). The responsiveness was evaluated by means of standardized effect size (SES) and standardized response mean (SRM) six months post surgical replacement. RESULTS: Cronbach´s alpha were all higher than 0.8 but in social activities dimension (0.64). Regarding test-retest reliability the ICCs were higher than 0.75 but in the social activities (0.4) and social support (0.4) dimensions. Finally, responsiveness parameters were: physical dimension (SES = 1.26; SRM = 0.89); pain (SES = 1.37; SRM =0.94); mental health (SES = 0.65; SRM = 0.56). CONCLUSIONS: These results support the validity and responsiveness of the Spanish version of the OAKHQOL a disease specific HRQoL questionnaire to be used in patients with osteoarthritis of the lower limb and surgical management