Inhaled Corticosteroid Replacement Study - Efficacy and Safety of Ro 27-2441 (Test Drug) in Moderate Persistent Asthma

Inclusion Criteria: * Persistent asthma for more than 1 year * Currently receiving treatment with a stable dose of inhaled corticosteroids for more than 3 months * In good health as demonstrated by medical history and physical exam * Negative urine pregnancy test * Commitment to use two forms of effective contraception simultaneously throughout the study duration and for 1 month after discontinuing therapy Exclusion Criteria: * Hospitalization for treatment of asthma and/or treatment with oral/injectable corticosteroids within 3 months before the start of the study * Undergoing allergy shots unless on a stable maintenance dose for 3 months before the start of the study * History of chronic pulmonary diseases other than asthma * Treatment of conditions other than asthma with oral corticosteroids within 1 month of the start of the study * Current tobacco usage * Smoking history of greater than 10 pack-year history of cigarette smoking (number of packs smoked per day times the number of years smoked) * History or evidence of drug or alcohol abuse * Diagnosis or evidence of an infectious illness within one month of Visit 1 * Clinically significant diseases as assessed by the study doctor * Participation in another clinical study with an experimental drug within one month of start of the study