The objective of this study was to investigate adiponectin levels in both plasma and synovial fluid of female patients with knee osteoarthritis (OA) and to analyze the correlation between adiponectin and degradation markers of cartilage matrix in synovial fluid. Thirty female patients with knee OA were enrolled in this study. Levels of adiponectin and degradation markers of cartilage matrix were measured using enzyme-linked immunosorbent assay. Adiponectin level in synovial fluid was significantly lower with respect to paired plasma level (0.93 ± 0.64 vs. 7.50 ± 3.29 μg/ml, P < 0.001). Correlation analysis showed that synovial fluid adiponectin significantly correlated with degradation markers of aggrecan, AGG1 (r = 0.441, P = 0.015) and AGG2 (r = 0.445, P = 0.014), but not significantly correlated with degradation marker of collagen II, CTX-II. These findings suggest that adiponectin might involve in the regulation of the degradation of cartilage matrix in OA.