Chronic obstructive pulmonary disease (COPD) is a complex disease, where the initial symptoms are often cough as a result of excessive mucus production and dyspnea. With disease progression several other symptoms may develop, and patients with moderate to severe COPD have often multiorganic disease with severely impaired respiratory dysfunction, decreased physical activity, right ventricular failure of the heart, and a decreased quality of life. In addition osteoporosis might develop possibly due to a number of factors related to the disease. We wanted to investigate the prevalence of osteoporosis in a population of patients with severe COPD as well as to correlate the use of glucocorticoid treatment to the occurrence of osteoporosis in this population. Outpatients from the respiratory unit with COPD, a history of forced expiratory volume in 1s (FEV1) less than 1.3 L, with FEV1% pred. ranging from 17.3% to 45.3% (mean 31.4%, standard deviation (sd) 7.3%). Patients between 50 and 70 years were included. Other causes of osteoporosis were excluded before inclusion. At study entry spirometry, X-ray of the spine (to evaluate presence of vertebral fractures), and bone mineral density of lumbar spine and hip were performed. Of 181 patients invited by mail, 62 patients were included (46 females and 16 males). All had symptoms of COPD such as exertional dyspnea, productive cough, limitations in physical activity etc. The mean FEV1 was 0.90 L (sd: 0.43 L) and the mean FEV1% pred. of 32.6% (sd: 14.1%). All had sufficient daily intake of calcium and vitamin D. In 15 patients, X-ray revealed compression fractures previously not diagnosed. Bone density measurements showed osteoporosis in 22 patients and osteopenia in 16. In total, 26 of the COPD patients were osteoporotic as evaluated from both X-ray and bone density determinations. Thus 68% of the participants had osteoporosis or osteopenia, but glucocorticoid use alone could not explain the increased prevalence of osteoporosis. A large fraction of these needed treatment for severe osteoporosis in order to prevent further bone loss and to reduce future risk of osteoporotic fractures. Thus, there is a significant need to screen patients with COPD to select the individuals in risk of fracture and to initiate prophylaxis or treatment for the disease.