Montelukast Post-Marketing Comparative Study With Ketotifen (0476-379)

Inclusion Criteria: * Intermittent asthma, mild persistent asthma, moderate persistent asthma, or severe persistent asthma patients with 2 or more mild or moderate attacks at baseline Exclusion Criteria: * Patient using anti-asthma treatment or therapy including corticosteroids or oral anti-allergic drugs * Patient with complications that will impair the judgment of efficacy of this drug * Patient with convulsive disorders such as epilepsy or such a history * Patient with liver disease, renal impairment, heart disease or such other complication