Osteoporosis affects 40% of white women older than 45 years of age and 15% of white men older than 50 years of age, resulting in approximately 1.5 million annual fractures in the United States. Systemic corticosteroid therapy increases the probability of osteoporosis, even with alternate-day dosing and with dosages sufficiently low so as not to affect the hypothalamic-pituitary-adrenal axis. Inhaled corticosteroid therapy may affect bone density if high-dose therapy is given to select individuals. The potential of increasing osteoporosis with inhaled corticosteroid asthma therapy is a concern because of the availability of more potent inhaled corticosteroid agents and recommendations that inhaled corticosteroid therapy be initiated earlier in the course of asthma. This article provides suggestions, on the basis of the medical literature and consensus of the authors when specific information was not available, for assessing and treating osteoporosis in subjects with asthma. Suggested risk categories are "low risk" (inhaled corticosteroid dosage of < or =800 microg of heclomethasone dipropionate [BDP]/day in adults or < or =400 microg BDP or equivalent in children), "moderate risk" (inhaled BDP >800 microg/day in adults or >400 microg/day in children), and "high risk" (systemic corticosteroid therapy 4 times a year or daily or alternate-day systemic corticosteroid therapy). Dosage of nasal corticosteroid probably should be added to the orally inhaled corticosteroid for total burden of inhaled corticosteroid. Potential treatment strategies based on risk factors and bone density if indicated are offered to assist physicians treating patients with asthma.