The aim of this study was to compare the efficacy and safety of once-daily ciclesonide, a new-generation, on-site-activated, inhaled corticosteroid, with once-daily budesonide in persistent asthma. Eligible patients requiring budesonide or equivalent 320-640 microg (ex-mouthpiece, equivalent to 400-800 microg; Turbohalertrade mark) daily entered a 2-week baseline, and then a 2- to 4-week pretreatment period (budesonide 1280 microg/day; ex-mouthpiece, equivalent to 1600 microg/day). Patients with an increase in forced expiratory volume in 1s (FEV1) of 7% or 0.15 L were randomised to ciclesonide 320 microg (ex-actuator, equivalent to 400 microg ex-valve) via a hydrofluoroalkane-metered dose inhaler (HFA-MDI) without a spacer or budesonide 320 microg once daily in the morning for 12 weeks. Change in FEV1 was the primary endpoint. In all, 359 patients were randomised. The FEV1 and forced vital capacity (FVC) decreased by 0.18 and 0.12L, respectively, in the ciclesonide group, and by 0.23 and 0.21L in the budesonide group. For FEV1, ciclesonide was noninferior and numerically superior to budesonide. For FVC, ciclesonide was statistically superior to budesonide (P=0.010). Asthma symptom scores were comparable; the median percentage of symptom-free days was significantly higher for ciclesonide (43.6%) versus budesonide (25.8%) (P=0.017). Rescue medication use decreased significantly only for ciclesonide patients (P=0.009). Frequency of adverse events was low in both groups. Ciclesonide 320 microg once daily by HFA-MDI without a spacer was at least as effective as budesonide 320 microg once daily in persistent asthma.