Published literature relevant to comparison of various inhaled corticosteroids (ICSs) was reviewed. Marked heterogeneity was found in the reported results. The efficacy and side effects of ICSs depend on their formulation, dosing and device used, and the subjects' age, severity of asthma, and inhaler technique. All these factors have not been included uniformly in most study designs. Notwithstanding this limitation, it appears that fluticasone is generally very effective and safe in low-to-medium doses and may be used for most patients. Budesonide is the only Pregnancy Category B ICSs, all others being Category C, and it is available as nebulizer suspension suitable for use in children over 6 months of age. Budesonide, also available as dry powder inhaler, and beclomethasone, available as metered-dose inhaler, are equal in efficacy, and side effects and may be chosen according to the patient's ability to handle the device. Flunisolide causes fewer side effects but is also relatively less effective. Triamcinolone is generally less effective and causes more side effects than most of the other ICSs. Mometasone may be preferred if once-daily dosing is desired. Ciclesonide has been found highly effective in once-daily dose and without side effects even in high doses. Further studies comparing it with other ICSs over longer periods of use will determine its place in treatment of chronic asthma.