The data available indicate that ROM, strengthening and aerobic conditioning exercises are safe for patients with OA, RA or AS, despite earlier concerns that exercise might exacerbate joint symptoms or accelerate disease. Less clear are the therapeutic benefits of exercise. In patients with OA, stretching, strengthening, and aerobic conditioning programmes can improve the deficits observed in these patients. The improvements observed generally have been small, and the evidence that these individual improvements result in improved overall function is minimal. None the less, it is likely that exercise will reduce pain, improve endurance for physical activities and improve cardiovascular fitness. Study of the long-term effects of exercise in the geriatric population, for sustaining independent living and functioning, is critically important for future health care and social expenditures. In RA, strengthening and aerobic conditioning exercise programmes can increase muscle strength and cardiovascular fitness and probably improve physical function as well. Improvements demonstrated in patients with RA seem more convincing than those in patients with OA and AS; this probably represents their poorer physical status prior to exercising. For patients with AS, intensive physiotherapy brings statistically significant short-term improvements in spinal and hip ROM which are only modestly clinically significant. It is possible that spinal mobility exercises decelerate loss of mobility over the long term, but controlled studies are needed to confirm this. Improvement in respiratory function with exercise appears to be related to cardiopulmonary fitness and perhaps to improvements in diaphragmatic respiration rather than to changes in thoracic cage mobility. Given the overall safety and likely benefits of the described forms of exercise, exercise should be included in the overall treatment of patients with OA, RA or AS. Careful patient evaluation and education about exercise should be a part of the exercise programme.