Studies of osteoarthritis (OA) in humans are restricted by the slow rate at which the disease progresses, and the limited opportunity for study of the tissue changes over time. A range of animal models of OA have been developed which demonstrate histopathological and gross features typical of OA in humans. Animal models can be used to study OA, and to investigate the effects of a variety of agents, including so-called chondroprotective agents, on the progression of the disease.