The aim of this study is to investigate visfatin levels in both synovial fluid (SF) and plasma of patients with primary knee osteoarthritis (OA) and its relationship with biomarkers of cartilage degradation in SF. Thirty OA patients, 12 SF control, and 12 plasma control subjects were enrolled in this study. Visfatin levels in both SF and plasma were measured using enzyme-linked immunosorbent assay (ELISA). Degradation biomarkers of collagen II and aggrecan in SF were also measured. The radiographic grading of OA in the knee was performed by the Kellgren-Lawrence (KL) criteria. Compared to controls, OA patients had higher SF visfatin concentration (8.95 ± 2.5 vs. 4.48 ± 2.49 ng/ml, P < 0.001). SF visfatin levels in KL grade 4 were significantly elevated compared with those of KL grade 3 (10.57 ± 2.49 vs. 7.54 ± 1.5 ng/ml, P = 0.001). SF visfatin positively correlated with degradation biomarker of collagen II, CTX-II (r = 0.497, P = 0.005), and degradation biomarker of aggrecan, AGG1 (r = 0.451, P = 0.012) and AGG2 (r = 0.434, P = 0.017). These findings suggest that SF visfatin might involved in cartilage matrix degradation.