Objective: The purpose of this study was to investigate whether radiographic scores correlate with histomorphological grading and expression of the hyaluronan receptor splice variant CD44v5 in osteoarthritic synovia, cartilage and synovial fluid. Methods: Synovia and cartilage specimens of 19 patients with osteoarthritis of the knee were histomorphologically evaluated with the Mankin’s score, and expression of CD44v5 was analyzed by immunohistochemistry. For radiographical scoring, weight-bearing radiographs of the knee joint were evaluated according to Kellgren and Ahlback. Levels of soluble CD44v5 in synovial fluids were determined by ELISA. Results: The mean radiological scores according to Kellgren and Ahlback were 3.79 and 3.21, respectively. Histomorphological evaluation of specimens revealed a mean grade of 5.53. There was no correlation between radiographical and histomorphological data. Expression of CD44v5 in synovia and cartilage samples was detected in about 50% of the patients and was restricted to latestage osteoarthritis. The immunohistochemical data obtained from synovia correlated significantly with radiological disease progression (p< 0.05). A highly significant correlation was evident between expression of CD44v5 in synovia and cartilage (p< 0.01). Synovial fluid levels of the soluble receptor form showed no correlation. Conclusion: Overall, this study emphasizes a combination of several independent parameters including radiography, histomorphology, and immunohistochemistry for accurate assessment of osteoarthritic disease progression. In this regard, CD44v5 may be a useful additional marker for late-stage osteoarthritis