Explorative comparison of montelukast with inhaled steroids (fluticasone) to estimate responder profiles, in terms of symptom scores, rescue medication, increase of FEV1, in correlation to presence of allergy, bronchial hyperreactivity (PD20), exhaled NO, excretion of leukotrienes, response to RABA and laboratory parameters in patients with pre-school asthma i.e. asthma phenotypes.

Inclusion Criteria:

• Male or female patients age 4 -6 years
• Diagnosis of mild intermittent bronchial asthma (Step I-II) in the past 6 - 12 months as stated by the investigator:
• Use of inhaled beta-2-agonists < 1/week (max 3 puff /d)
• Exacerbation-free interval > 4 weeks prior to visit 1
• The written informed consent of parents after received written and oral information about the aim, purpose and risks of the study must be present

Exclusion Criteria:

• Asthma severity ≥ Step 2
• Severe concomitant diseases
• Suspected non-compliance
• age below 4 and age above 7 years
• last study participation < 30 days