Osteoarthritis is a chronic disease characterised by irreversible damage to joint structures, including loss of articular cartilage, osteophyte formation, alterations in the subchondral bone and synovial inflammation. Pain, functional disability and impairment of health-related quality of life are major complaints in patients with osteoarthritis. Several compounds have been investigated for their positive effects on the relief of clinical symptoms and improvement of structural changes in osteoarthritis. It has been shown that chondroitin sulphate interferes with the progression of structural changes in joint tissues and is used in the management of patients with osteoarthritis. This review summarises data from relevant reports describing the mechanisms of action of chondroitin sulphate involved in the beneficial effects of the drug.