Synovium is an essential component of the joint and plays a critical role in maintaining a balance between physiological processes and pathological changes in the joint. Recurrent intra-articular bleeding as occur in haemophilia induce pathological synovial changes in the joint. From a certain point on, synovitis inevitably plays a major role in joint destruction, although in the early phase of haemophilic arthropathy its role may be secondary to cartilage damage as a result of the direct effects of blood on cartilage. The changed haemosiderotic, synovial tissue produces catabolic cytokines and enzymes harmful for cartilage.