Objective:To study the relation shipbetween lung function and bone mineral density(BMD),serum Vitamin D in elderly patients with chronic obstructive pulmonary disease(COPD). Methods:Pulmonary function,BMD of lumbar spine and femoral neck,and serum Vitamin D were determined in 104 COPD(61 male,43 postmenopausal female) patients and 100 cases age and sex matched non-COPD controls. The association of lung function and BMD with serum vitamin D was analyzed as well. Results:Vitamin D insufficient and osteopenia were present in elderly men.The prevalence of Vitamin D deficiency and osteoporosis was higher in COPD group than that in non-COPD controls (37.5% vs 16.0% and 38.5% vs 20.0%)(P < 0.05). The increase of COPD severity led to the decrease of average values of BMD of femoral neck (P < 0.05),as well as Vitamin D (P < 0.05). Correlation analysis showed that BMD and Vitamin D were correlated to FEV1(P < 0.05). Conclusion:Prevalence of Vitamin D deficiency is high in COPD patients,increases with the severity of COPD,and is closely associated with osteoporosis prevalence. BMD and Vitamin D were correlated to pulmonary function.