Ten asthmatic patients receiving long term treatment with high dose of inhaled beclomethasone dipropionate (BDP) (750 to 2,250 micrograms/die, average 1,400 +/- 474 micrograms) underwent evaluation of hypothalamic-pituitary-adrenal (HPA) axis under basal conditions (serum cortisol and ACTH levels at 8.00 AM and 8.00 PM, 24-hours free urinary cortisol) and by means of pharmacological tests (short tetracosactide and Corticotrophin Releasing Factor Tests). Basal ACTH serum levels at 8.00 PM were lower than the normal values in all patients: three patients had reduced 24-hr free urinary cortisol and six subjects showed lower cortisol serum levels at 8.00 PM. A normal response to the short tetracosactide test was observed in all patients, whilst Corticotrophin Releasing Factor (CRF) induced an increase in ACTH and cortisol levels (expressed as delta AUC) that was significantly lower in the BPD treated patients compared with a control group of five healthy subjects (p < 0.05). Thus BPD, in high doses, may cause a partial inhibition of HPA axis. Our results show that determination of basal ACTH level and CRF test are more sensitive than serum cortisol levels and short tetracosactide test to evaluate a suppression of HPA axis in patients receiving long term inhaled high doses of BDP.