Corticosteroids (CS) have been used for many years and proved to be the most effective treatment in asthmatic patients. They are controllers of choice in the management of most adult patients with asthma. CS reduce asthma symptoms, improve lung function, reduce frequency of asthma attacks, hospital admissions and asthma mortality. CS prevent reversible airway narrowing but the effects wane after discontinuing the therapy. CS inhibit the synthesis of many cytokines involved in asthmatic inflammation. They suppress inflammation but do not cure underlying cause. The choice of inhaled steroid depends on their pharmacologic properties (receptor affinity and systemic bioavailability). There is no convincing evidence that regular use of combination of inhaled corticosteroid and long acting-b-agonists (LABA) provides any additional benefit in patients with mild asthma. It seems that the optimal management of mild asthma is occasional use of combined therapy when symptoms are present. Long-term combined therapy with inhaled corticosteroid and LABA is still a "golden standard" in patients with moderate and severe asthma. Corticosteroids are also used in chronic obstructive pulmonary disease (COPD) patients. Medication with CS can reduce symptoms but does not alter the course or progression of COPD. There is no effect of corticosteroids on all cause mortality in COPD patients. No suppression of inflammation was found in COPD patients treated with inhaled and oral corticosteroids, even at high doses. There is a small beneficial effect of CS against acute exacerbations in patients with severe disease, with improved clinical outcome and reduced length of hospital admission. Combination inhalers that include a LABA and CS are more effective then either component alone.