Inhaled corticosteroids (ICS) are the most effective therapy for asthma currently available. The increasing use of ICS raises the issue of possible adverse systemic effects. Since one of the most important side-effects of oral corticosteroids (OCS) is osteoporosis, this article focuses on current knowledge of the effects of ICS on bone. Generally, doses higher than 1.0 mg/day cause a dose-dependent decrease in serum osteocalcin levels. Decreases in bone density have been suggested after treatment with ICS, but in most studies it is impossible to quantify the contribution of previous treatment with OCS and other confounding factors to bone loss. The clinical relevance of the observed changes in the long term is unknown. To date,