To assess validity and reliability of the Western Ontario and McMaster Universities (WOMAC) osteoarthritis (OA) index and Lequesne algofunctional index in Turkish patients with hip or knee OA and to compare the results of the instruments for these two particular sites of involvement. Two disease-specific instruments: WOMAC LK 3.1 and Lequesne indices were administered to 117 outpatients with OA (44 hip and 73 knee) living in Turkey. These indices were administered twice 7-10 days apart to ensure the test-retest reliability. All patients were asked to reply a generic health-related quality-of-life instrument (Short Form-36, SF-36) and a structured interview assessing demographic and other characteristics. Internal consistency and reliability was evaluated by Cronbach's alpha and intra-class correlation coefficients (ICC). Construct validity was tested by correlating the WOMAC or Lequesne with each other, and also with SF-36 and visual analog scale (VAS). The Cronbach's alphas of the WOMAC and Lequesne subscales were ranged 0.78-0.95 and 0.51-0.85 for hip and 0.78-0.94 and 0.61-0.71 for knee OA, respectively. Test-retest reliability of the WOMAC and Lequesne subscales yielded ICCs of 0.77-0.94 and 0.51-0.85 for hip and 0.80-0.98 and 0.61-0.71 for knee OA, respectively. WOMAC and Lequesne showed moderate-good correlations between comparable subscales of SF-36 (physical functioning and bodily pain) and weak-moderate correlations between VAS. All subscales and total WOMAC had better internal consistency and more satisfactory concurrent validity compared with Lequesne. Our results indicated that WOMAC is a more reliable index for use in Turkish patients with hip or knee OA than Lequesne.