Disability associated with chronic obstructive pulmonary disease has led to the development of rehabilitation programmes that aim to increase exercise tolerance and improve quality of life. Many reports of the benefits of rehabilitation have been from uncontrolled trials and unsupervised programmes. In view of the commitment asked of patients, their families, and health-care professionals, rehabilitation should be justified by a demonstration of sustained improvement over conventional treatment. We undertook a prospective randomised controlled trial of respiratory rehabilitation in 89 subjects (44 men, 45 women) aged 66 (SD 7) years with severe but stable chronic obstructive pulmonary disease who received rehabilitation or conventional community care. The treatment group were rehabilitated as inpatients for 8 weeks and supervised as outpatients for 16 weeks. Primary outcome measures of exercise tolerance and quality of life were made at baseline and repeated at 12, 18, and 24 weeks. The difference between baseline and last follow-up was significant for 6 min walk distance (37.9 m [95% CI 10.8-65.0], p = 0.0067) and submaximal cycle time (4.7 min [2.1-7.3]). There were also significant differences in questionnaire assessment of dyspnoea (p = 0.0061), emotional function (p = 0.0150), mastery (p = 0.0002), and dyspnoea index (p = 0.0053). Improvements in exercise tolerance and quality of life can be achieved and sustained for 6 months in patients undergoing respiratory rehabilitation compared with those receiving conventional care.