Glucocorticosteroids (GS) being widely used in asthma treatment are sometimes applied in high doses and for long period. This treatment is often connected with adrenocortical suppression. Adrenocortical function assessment in GS treated patients with different doses and forms of drug is of great diagnostic and prognostic importance. In the presented work the methods of adrenocortical function assessment are discussed, especially serum cortisol level and non-invasive: saliva and urine cortisol assays.