QUESTION: Is therapeutic exercise of benefit? DESIGN: A summary of systematic reviews on therapeutic exercise published from 2002 to September 2005. PARTICIPANTS: People with neurological, musculoskeletal, cardiopulmonary, and other conditions who would be expected to consult a physiotherapist. INTERVENTION: Therapeutic exercise was defined as the prescription of a physical activity program that involves the client undertaking voluntary muscle contraction and/or body movement with the aim of relieving symptoms, improving function or improving, retaining or slowing deterioration of health. OUTCOME MEASURES: Effect of therapeutic exercise in terms of impairment, activity limitations, or participation restriction. RESULTS: The search yielded 38 systematic reviews of reasonable or good quality. The results provided high level evidence that therapeutic exercise was beneficial for patients across broad areas of physiotherapy practice, including people with conditions such as multiple sclerosis, osteoarthritis of the knee, chronic low back pain, coronary heart disease, chronic heart failure, and chronic obstructive pulmonary disease. Therapeutic exercise was more likely to be effective if it was relatively intense and there were indications that more targeted and individualised exercise programs might be more beneficial than standardised programs. There were few adverse events reported. However, in many areas of practice there was no evidence that one type of exercise was more beneficial than another. CONCLUSION: Therapeutic exercise was beneficial for patients across broad areas of physiotherapy practice. Further high quality research is required to determine the effectiveness of therapeutic exercise in emerging areas of practice.