OBJECTIVES: Ciclesonide is a novel inhaled corticosteroid (ICS) for anti-inflammatory asthma therapy. Patients' perception of ICS-related side effects is not only important for treatment satisfaction but might also have a major impact on compliance. We used the new self-administered Inhaled Corticosteroid Questionnaire (ICQ) to compare patient-perceived side effects in a 12-week, open-label, parallel-group study with ciclesonide or fluticasone propionate (FP). METHODS: During the baseline period (1-4 weeks), patients received either FP£250 µg/d (or equivalent) or rescue medication only. Patients (n=472, intention-to-treat population; 12-74 years) with FEV1 60-80% predicted (rescue medication) or ³80% predicted (low dose ICS) and defined criteria for rescue medication use and asthma symptoms were centrally randomized by IVR system to receive either 320µg ciclesonide once daily (ex-actuator, HFA-MDI), or 200µg FP twice daily (Diskus®). Patients completed the ICQ (57 questions, 7-point scale, 15 domains) at start and end of the treatment. ICQ data were analysed by non-parametric methods for differences between ciclesonide and FP. Intention-to-treat analysis was of primary interest. RESULTS: After 12 weeks, the ICQ overall score did not change significantly in the ciclesonide group (+0.22, p=0.4200, two-sided), whereas statistically significantly increased (corresponding to patient-perceived worsening of the condition) in the FP group (+1.36, p=0.0003, two-sided). Similarly, there was no significant change in the ICQ domain scores in patients treated with ciclesonide, whereas with FP significant increases (p£0.0006, two-sided) occurred in the domain scores ′unpleasant taste′ (+1.19) and ′voice problems′ (+2.22). Ciclesonide was superior to FP regarding to changes in ICQ overall score (point estimate –0.87, p=0.0205, one-sided) and domain score ′voice problems′ (point estimate –1.36, p=0.0036, one-sided). CONCLUSION: ICS-related side-effects as perceived by patients with moderate asthma worsened with the relative low dose of FP 200µg twice daily, but did not change with ciclesonide 320µg once daily after 12 weeks of treatment.