Patients with chronic obstructive pulmonary disease (COPD) are at increased risk of osteoporosis. However, the prevalence, correlates and effectiveness of treatment of osteoporosis in COPD patients remain unclear. We performed a systematic review of the literature to answer three questions. 1) What is the prevalence of osteoporosis in COPD? 2) What are identified correlates of osteoporosis in COPD? 3) What are the effects of treatment of osteoporosis in COPD? A computerised literature search in MEDLINE/PubMed and the Cochrane database was carried out. In addition, reference lists were searched by hand and authors were contacted if necessary. The prevalence of osteoporosis and osteopenia varied 9-69% and 27-67%, respectively. Prevalence of osteoporosis was generally higher than in healthy subjects and some other chronic lung diseases. Correlates of osteoporosis in COPD are mainly measures of body composition, disease severity and the use of corticosteroids, although causality has not been proven. Effects of treatment of osteoporosis have not been investigated in samples consisting of COPD patients only. Longitudinal follow-up to assess determinants of osteoporosis in COPD and randomised placebo-controlled trials on the effects of treatment of osteoporosis in patients with COPD only are warranted.