Study Of Asthma In Patients Of African Descent

Inclusion criteria: * History of asthma for at least 6 months. * Taking a low-dose of an inhaled corticosteroid for at least one month prior to the study (such as fluticasone propionate or budesonide). Exclusion criteria: * History of life-threatening asthma. * Hospitalized for asthma within 3 months prior to the study. * Current respiratory tract infection. * Will not be able to attend clinic visits for the entire length of the study. * Certain medical conditions that will make being in the study unsafe (such as congestive heart failure, uncontrolled hypertension, tuberculosis or certain drug allergies).