We compared the reliability, validity, and responsiveness of the Musculoskeletal function Assessment (MFA) questionnaire with those of three commonly used health-status measures: the Short Form-36 (Sf-36), the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and the Sickness Impact Profile (SIP). The MFA, like the other health-status measures, demonstrated good reliability (intraclass correlation coefficient of more than 070), good sensitivity and specificity (more than 70 per cent), good criterion validity that correlated with physicians' ratings (p <0.01), and good construct validity that correlated with the characteristics of the patients (p <001). It also demonstrated better content validity than the other questionnaires, with no ceiling or floor effects for the total score. In addition, it was more responsive than the SF-36; for eight of the eleven comparisons, it was more efficient (relative efficient of more than 200) in measuring changes in function between the baseline values and the values determined at the latest follow-up evaluation. Theses findings suggest that the MFA can be used to assess the health status of patients who have a musculoskeletal disorder.