BACKGROUND Quantitative ultrasound bone densitometry (QUBD) is a new method to assess bone mineral density and bone microarchitecture. Corticosteroid (CS) therapy may diminish bone mass, alter bone quality and may influence growth hormone (GH) secretion and bone metabolism markers. Therefore, the aim of this study was to evaluate the effects of long-term therapy with inhaled CSs (ICSs) on structural bone characteristics and their correlations with GH secretion and bone markers in asthmatic patients. METHODS In a cross-sectional study, we enrolled 60 adult patients with mild to moderate persistent asthma: 22 on chronic (>1 year) ICS therapy, 10 naive to ICSs treatment and 28 healthy control subjects. The groups were matched for age and BMI. Each subject underwent to QUBD at the phalanxes to assess bone microarchitecture by ultrasound bone profile index (UBPI), bone density by amplitude-dependent speed of sound (AdSos); test with GH-releasing hormone (GHRH) injection with calculation of peak GH and the Delta GH (peak GH-basal GH); and hormonal and bone markers measurements. RESULTS Asthmatics treated with long-term ICS therapy showed a lower UBPI (P < 0.01) compared to controls (49.8 +/- 19.3 vs. 77.0 +/- 10.1, respectively) and to asthmatics never taking ICSs (73.2 +/- 9.6). In ICS-treated asthmatics, DeltaGH and GH-peak showed a significant correlation with UBPI. A significant difference was observed comparing asthmatics treated with ICSs to controls and asthmatics naive to ICSs in GH response to GHRH iv bolus. Serum osteocalcin was significantly reduced in asthmatic patients treated with ICSs. CONCLUSIONS In asthmatic patients, long-term ICSs treatment produces negative effects on bone quality assessed by QUBD, and such effects are associated to an impaired GH secretion.