Conventional metered-dose inhalers and dry powder inhalers are used by most adult patients with asthma and chronic obstructive pulmonary disease who receive inhaled corticosteroid therapy. There are circumstances, however, in which nebulized inhaled corticosteroid delivery may provide greater clinical benefit to these patients. This review discusses the efficacy and safety of nebulized inhaled corticosteroid therapy in adult patients with asthma or chronic obstructive pulmonary disease for whom nebulized therapy may be preferable.