The purpose of this study is to determine the appropriate dose of Ro 27-2441 (test drug) to be used in future studies, assess the efficacy and safety, and the anti-inflammatory action of the test drug in the treatment of asthmatic patients who are not currently receiving chronic therapy with corticosteroids. The research is being conducted at up to 80 clinical research sites in the US, Mexico, and Canada. Study participants will have a number of visits to a research site over approximately a 4-month period.