Bone mass and biochemical bone markers were prospectively studied in 33 patients with chronic obstructive pulmonary disease treated for 1 year with inhaled beclomethasone 200 micrograms/q.i.d. (group A, 8 men and 4 women), inhaled budesonide 200 micrograms/q.i.d. (group B, 6 men and 5 women), or not requiring steroids (group C, 6 men and 4 women). Both inhaled corticosteroids decreased serum concentrations of the osteoblastic markers, osteocalcin and carboxy-terminal propeptide of type I collagen (PICP). The osteoclastic marker cross-linked carboxy-terminal telopeptide of type I collagen (ICTP) increased significantly more in patients on beclomethasone than in those on budesonide. The decrease in bone mineral density was more pronounced in patients treated with beclomethasone (1.1% in the spine 1.7% in the hip P < 0.05) compared to those treated with budesonide (0.6% in both spine and hip) or in the control group. Inhaled corticosteroids affect biochemical bone markers and bone mineral density, but there is a different effect for the two corticosteroids evaluated in the present study.