Tendons are frequently affected by chronic pain or rupture. Many causative factors have been implicated in the pathology, which until relatively recently was under-researched and poorly understood. There is now a greater knowledge of the molecular basis of tendon disease. Most tendon pathology (tendinopathy) is associated with degeneration, which is thought to be an active, cell-mediated process involving increased turnover and remodelling of the tendon extracellular matrix. Degradation of the tendon matrix is mediated by a variety of metalloproteinase enzymes, including matrix metalloproteinases and 'aggrecanases'. Neuropeptides and other factors released by stimulated cells or nerve endings in or around the tendon might influence matrix turnover, and could provide novel targets for therapeutic intervention.Tendons are dense, fibrous connective tissues that connect muscle to bone and are essential for the transmission of force and the generation of movement at a joint. They are highly ordered composite materials consisting of collagens, proteoglycans and various glycoproteins, many of which have been poorly characterised. Tendon problems such as tendon rupture and chronic tendon pain are common, although the underlying pathology is not well understood and the conditions are often difficult to treat (Ref.