The use of inhaled glucocorticosteroids for the treatment of asthma raises the important question of short- and long safety. Thus the assessment of the benefit-risk ratio is an essential part of the development of powerful agents with reinforced topical activity. Several factors determine the optimal profile for an inhaled glucocorticoid: topical activity, systemic bioavailability (influence of the first-pass liver metabolism, inhalation device, patient- and disease-related factors), and pharmacokionetic behavior, liposolubility being one of the determining elements. Taken together these different factors produce a therapeutic index expressing the topical and systemic effects of inhaled glucocorticosteroids and their variability under the particular conditions of each patient. Al high-dose inhaled glucocorticoids have an impact on the adrenal gland which is easy to demonstrate but with rather insignificant clinical relevance. In children for example, there is a transient inhibition of bone growth with no impact on final height in adulthood. In adults; the effect on bone metabolism raises the risk of osteoporosis which must be prevented and detected in patients at risk. More data must be acquired concerning the ocular risk. Overall, significant adverse systemic effects are not observed with administration of inhaled glucocorticoids, but there remains a certain degree of uncertainty concerning the effects of long-term administration of low effective doses.