Rationale: Skeletal muscle strength and bulk are reduced in patients with COPD and influence quality of life, survival and utilisation of health care resources. Exercise training during pulmonary rehabilitation (PR) can reverse some of these effects. In athletes and healthy elderly, dietary creatine supplementation (CrS) has shown to augment high-intensity exercise training, thereby increasing muscle mass. Objectives: This paper examines the effect of CrS on functional exercise capacity and muscle performance in people with COPD. Design: Double blind, placebo-controlled, parallel group trial. Methods: One hundred subjects with COPD (mean (SD) age 68.2 (8.2) years, FEV₁ 44.0 (19.6) percent predicted) were randomised to a double blind, placebo-controlled, parallel group trial of CrS during 7-weeks of PR encompassing aerobic and resistance exercises. Subjects ingested creatine (22g/day loading for 5-days, maintenance 3.76g/d throughout PR) or placebo. Baseline, post-loading and post-rehabilitation measurements included pulmonary function, body composition, peripheral muscle strength and functional performance (shuttle walking tests). A volunteer subgroup (n=31) had pre- and post-loading quadriceps muscle biopsies. Results: Eighty subjects completed the trial (38 creatine, 42 placebo). All outcome measures significantly improved after PR. There were no significant differences between groups post PR (mean(SD) change incremental shuttle walk distance 84(79)m creatine vs. 83.8(60)m placebo; p = 1.0, knee extensor work 19.2(16)Nm creatine vs. 19.5(17)Nm placebo; p = 0.9). Muscle biopsies showed evidence of creatine uptake. Conclusion: This adequately powered, randomised, placebo-controlled trial shows that creatine supplementation does not augment the substantial training effect of multidisciplinary pulmonary rehabilitation for patients with COPD. Clinical trial registry: http://www.nrr.nhs.uk/search.htm, i.d. = N0123138126