A Study to Determine the Efficacy and Safety of Two Mometasone Dry Powder Inhalers in the Treatment of Asthma (Study P02524)

Inclusion Criteria: * Must be \>=18 years of age, of either gender \& of any race. * Must have had a diagnosis of asthma for at least 6 months, characterized by recurrent episode of wheezing, breathlessness, chest tightness \& coughing. * Baseline FEV1 must be \>=55% and \<=85% of predicted at the Screening Visit, when all restricted medications have been withheld for the specified intervals. * Must demonstrate evidence of an increase in absolute FEV1 of \>=12%, with an absolute volume increase of at least 200 mL, after reversibility testing at the Screening Visit or documented in the patients chart reversibility up to 1 year previous to inclusion. * Must be free of any clinically significant disease (other than asthma), that would interfere with study evaluations. * Must be willing to give written informed consent and be able to adhere to dose \& visit schedules. * Must agree to inform their own usual treating physician about their participation in the study. * Non-pregnant women of childbearing potential must be using a medically acceptable, adequate form of birth control. This includes: 1) hormonal contraceptive as prescribed by a physician (eg, oral combined, hormonal implant, depot injectable); 2) medically prescribed IUD; 3) condom in combination with a spermicide; 4) Monogamous relationship with a male partner who has had a vasectomy or is using a condom plus spermicide during the study. They must have started this birth control method at least 3 months prior to Screening (with the exception of condom in combination with a spermicide), \& must agree to continue its use for the duration of the study. Women of childbearing potential who are not currently sexually active must agree and consent to using a double-barrier method should they become sexually active during the course of this study. Women who are surgically sterilized or are at least 1 year postmenopausal are considered not to be of childbearing potential. However, all female subjects must have a urine pregnancy test obtained at screening, prior to initiation of treatment, \& at the end of the trial, which must be negative. * Subjects who did not use the following medication prior to inclusion: * Beta 2 agonist short-acting (inhaled, oral)(12 Hours) * Beta 2 agonist long-acting (inhaled)(48 Hours) * Ipratropium bromide (12 hours) * Cromolyn sodium, nedocromil (7 days) * Astemizole (3 months) * Cetotifeno (3 months) * Another investigational drug (1 month) * Theophyline (2 weeks) * Antihistamines (7 days) * Anticholinergics (7 days) * Leukotriene modifiers (2 weeks) * Oral decongestant long-acting (72 hours) * Oral decongestant short-acting (24 hours) * Oral corticosteroids (1 month) * Injected corticosteroids (3 months) * Inhaled corticosteroids (24 hours) * Baseline portable Peak Expiratory Flow at the Screening Visit must be \>50% of predicted. The best value out of 3 must be considered. Exclusion Criteria: * Women who are pregnant, breast-feeding, or are pre-menarcheal. * Have used any investigational drug within the last 30 days or who have ever been treated with any investigational antibody for asthma or rhinitis. * Are receiving escalating doses of immunotherapy, oral immunotherapy or short course (rush) immunotherapy. * No subject participating in this study may participate in this same study at another investigational site or in any other investigational study at the same time. * Must not be randomized into the study more than once. * Subjects with the following clinical conditions/demography: * Allergic to corticosteroids or beta-agonists. * Required hospitalization for asthma control within the previous 3 months. * Required ventilator support for respiratory failure secondary to their asthma within the last 5 years. * Treated in the ER (for a severe asthma exacerbation), or admitted to the hospital for management of airway obstruction, on 2 or more occasions within the last 6 months. * Clinical evidence of emphysema, chronic bronchitis, bronchiectasis, or cystic fibrosis. * Significant history of renal, hepatic, cardiovascular, metabolic, neurologic, hematological, respiratory, gastrointestinal, cerebrovascular, or other significant medical illness or disorder which, in the judgment of the investigator, could have interfered with the study, or required treatment which might have interfered with the study. * Requiring the use of \>12 puffs per day of Salbutamol on any 2 consecutive days between study visits. * Experienced upper or lower respiratory tract infection within the previous 2 weeks prior to enrollment. * Clinically relevant abnormal baseline vital sign. * Clinically significant abnormalities on chest x-ray at the Screening Visit or within the previous 6 months. * Evidence of clinically significant oropharyngeal candidiasis. * Smokers, or ex-smokers who are smoking or have smoked at least 20 years/pack or subjects who are smoking in the last 6 months. * Known to be HIV positive. * Known to be illicit drug abusers. * HPA axis disturbances. * Showing any clinical condition considered to be severe. * Severe airflow obstruction showing to be life-threatening. * Baseline FEV1 \<55% of the predicted normal. * Uncontrolled hypertension. * Suspected pneumonia, pneumothorax, pneumomediastinum, pulmonary TB, alpha-1 anti-trypsin deficiency, lung mycosis or pulmonary cystic fibrosis. * History of thoracic surgery or any previous malignancy of the lung, * Significant heart disease, * Receiving beta-adrenergic blocking agents. * Presenting baseline portable peak expiratory flow at the Screening Visit \<=50% of predicted. The best value out of 3 must be considered.