The aim of this study is to compare the efficacy of ciclesonide with respect to reduction of the number of asthma exacerbations in children with mild persistent asthma. Treatment medication will be administered as follows: ciclesonide will be inhaled once daily, using one of the two dose levels versus placebo together with other corticosteroids used as intermittent treatment. The study duration consists of a baseline period (3 to 4 weeks) and a treatment period (12 months). The study will provide further data on safety and tolerability of ciclesonide.