The aim of the study is to compare the effects of oral roflumilast with placebo on lung function in patients with asthma.

Main Inclusion Criteria:

• Persistent bronchial asthma
• No change in asthma treatment within 4 weeks prior to visit 1
• Non-smoker or ex-smoker (for 12 months or longer)

Main Exclusion Criteria:

• Poorly controlled asthma or seasonal asthma
• History of lower airway infection four weeks prior to visit 1
• Chronic obstructive pulmonary disease (COPD) and/or other relevant lung disease
• Patients using > 8-puffs/day-short-acting bronchodilator (beta-agonists) (more than 3 days per week on average) prior to visit 1
• Clinically relevant abnormal laboratory values suggesting an undiagnosed disease, severe renal insufficiency, active hepatitis or an HIV infection
• Diagnosis, treatment or remission of any cancer (other than basal cell carcinoma) within two years prior to visit 1
• Patients with chronic heart failure
• Suspected hypersensitivity and/or contraindication to roflumilast or albuterol/salbutamol
• Female patients of childbearing potential not using adequate means of birth control or pregnant or breast-feeding females
• Patients who have received any investigational medication or device in the month prior to visit 1 or who plan to use another investigational medication during the study