Aim: This investigation intends to assess the potential utility of COMP and YKL 40 as biochemical indicators of osteoarthritic condition in persons with knee osteoarthritis (OA). Methods: This study included as controls 40 patients with symptomatic knee OA who met ACR criteria for idiopathic knee OA and 15 healthy volunteers matched for age and gender. Using ELISA, COMP and YKL-40 serum levels were determined. Among our OA patients, we associated the levels of these markers with changes in Kellgren Lawrence (K-L.) grade, joint space width (JSW), age, disease duration, gender, body mass index (BMI), and western Ontario MacMaster (WOMAC) index. Results: There were significant elevations of the serum COMP and YKL-40 in OA patients in comparison to the control group (P