The aim of the study is to investigate the efficacy of ciclesonide versus budesonide on lung function, symptoms and use of rescue medication in patients with asthma. Ciclesonide and budesonide will be inhaled once daily at one dose level each. The study duration consists of a baseline period (1 to 4 weeks) and a treatment period (12 weeks). The study will provide further data on safety and tolerability of ciclesonide.

Main Inclusion Criteria:

• During the last 4 weeks prior to baseline, treatment with an inhaled steroid (dosage: up to 250 mcg fluticasone propionate or equivalent)
• FEV1 80 - 105% of predicted
• Healthy with the exception of asthma
• Written informed consent has been obtained
• Outpatients
• Patients who have a history of persistent bronchial asthma for at least 6 months

Main Exclusion Criteria:

• Concomitant severe diseases or diseases which are contraindications for the use of inhaled steroids
• Concomitant COPD (i.e. chronic bronchitis or emphysema) and/or other relevant lung diseases causing alternating impairment in lung function
• An asthma exacerbation or an infection of the lower airways prior to entry into the baseline period
• Pregnancy
• Intention to become pregnant during the course of the study
• Breast feeding
• Lack of safe contraception
• Patient is current smoker with 10 or more pack-years
• Patient is ex-smoker with 10 or more pack-years