The study will examine if ONO-6950 could alleviate EIB in asthmatic patients. Eligible patients will complete a randomized, double-blind, four-way crossover study. During each of four evaluation periods, patients will be administered a single dose of either 20 or 200 mg ONO-6950, 10 mg Montelukast, or placebo. Each evaluation period include various assessments following exercise challenge in an ambulatory setting.