Animal experiments with chemically induced osteoarthrosis in the knee joint of adult hens have shown that the daily treatment with tribenoside (Glyvenol(R)) using single oral doses of 50 mg/kg or 150 mg/kg, will result in a marked reduction of the intensity and frequency of joint degenerations. This anti-arthrotic effect was quantitatively measured by radiographic and macroscopic methods over a period of 3 months. In the present study we investigated the inhibitory effect of tribenoside on osteoarthrosis by histological techniques. Histological sections of osteoarthrotic articular cartilage of untreated and treated animals were compared and clearly indicated that there were no qualitative differences in alterations of the morphology and histopathology of the tribenoside treated specimen. Only the frequency and intensity of degenerative alterations where markedly reduced in the drug treated animals. Biochemical analysis of joint cartilage demonstrated that tribenoside (150 mg/kg) significantly reduced the loss of proteoglycans in the osteoarthrotic cartilage matrix. Our histological and biochemical findings are in good correlation with the results of our radiographic and macroscopic studies on the effect of tribenoside on experimental osteoarthrosis. The present investigation indicates that tribenoside exerts its antiarthritic effect on the base of its vasotropic properties by stabilization of the capillary system and membrane of the synovial tissue, which provides the transport and exchange of nutritional substrates and metabolites via synovial fluid to or from the articular surface. Our histological findings do not exclude the possibility that tribenoside also has a direct chondroprotective effect.