Inclusion criteria:

• Male or female subjects aged 6-12 years (inclusive)
• A female is eligible to enter and participate in the study if she is:

of non-child-bearing potential; OR of child-bearing potential, but not lactating and pregnant. She declares that it is not probable that she will become pregnant during the study (a pregnancy test can be performed at the investigators discretion)

• Subjects with a documented history of asthma for at least 6 months
• Subjects with a documented history of BHR within 12 months prior to inclusion or BHR on visit 1 (PD20 methacholine < 150 mcg or an equivalence for histamine)
• Subjects who have received BDP, budesonide up to 100-200 mcg bd or fluticasone propionate at a dose of up to 125 mcg bd for at least 4 weeks before the start of the run-in period.
• Subjects who are able to use a electronic peakflow /FEV1 meter (PIKO-1)
• Subjects who have a normal length SD score between -2SD and +2SD
• Subjects who are able to use a Diskus inhaler
• Subjects who are able to perform reproducible lung function tests at visit 1 (variation FEV1 < 5% between the two best measurements)
• Subjects and their guardians, who have given written informed consent to participate in the study
• Subjects or their parent/ guardian who are able to understand and complete a DRC. The DRC may be completed by a parent/guardian if the subject is unable to do this him/ herself
• Subjects able to use Ventolin on an 'as required for symptoms' basis

Exclusion criteria:

• Subjects who have been hospitalised for their asthma within 4 weeks of visit 1
• Subjects who had an acute upper respiratory tract infection within 2 weeks or a lower respiratory tract infection within 4 weeks prior to visit 1
• Subjects who received oral, parental or depot corticosteroids within 4 weeks prior to visit 1
• Subjects who have a known respiratory disorder other than asthma and/or systemic/thoracic abnormalities which influence normal lung function
• Subjects with a disorder that affects growth (e.g. Turner's syndrome)
• Subjects who have received any investigational drugs within 4 weeks of visit 1
• Subjects with a known or suspected hypersensitivity to inhaled steroids, β2-agonists or lactose
• Subjects who use any medication that significantly inhibit the cytochrome P450 subfamily enzyme CYP3A4, including ritonavir and ketoconazole
• Subjects who concurrently participate in another clinical study
• Subjects who have previously been randomised in this trial