We assessed the effect of long‐term therapy with inhaled beclomethasone dipropionate (BDP) on the pituitary—adrenal axis, by measuring the integrated concentration (IC) of plasma cortisol in eight children with asthma (age, 6–16 years) who regularly used inhaled BDP in doses ranging from 8 to 26.5 μg/kg (200–450 μg/day) for 6 months to 4 years. The control group included six children (age, 6–16 years) who had the IC of plasma cortisol measured as part of an endocrinological evaluation and were found to be healthy. Cortisol concentration was measured in blood samples collected continuously over a 24‐hr period. Mean IC of plasma cortisol in the study group was significantly lower than in the healthy controls (mean ± SD, 4.9 ± 3.3 vs 9.1 ± 1.9 μg/mL P < 0.02). Cortisol response to 0.25 mg ACTH (iv) was abnormal in one of the eight BDP‐treated patients. No correlation was found between IC of plasma cortisol and the BDP dose, severity of asthma, height percentile, or the Tanner stage. We conclude that long‐term therapy, even with relatively conventional doses of inhaled BDP may cause reduction in the normal physiological secretion of cortisol. The clinical relevance of low IC of plasma cortisol is not clear, but it may reflect partial suppression of the pituitary—adrenal axis.