Comparison of Efficacy and Safety of Azelaic Acid 15% Gel With Its Vehicle in Subjects With Mild to Moderate Acne

Inclusion Criteria: To be included in the study you MUST have: * Predominantly facial localization of acne * Mild to moderate acne vulgaris characterized by the presence of both inflammatory papules and/or pustules, and comedones (whiteheads/blackheads), and of a severity suitable for treatment with topical single therapy. * a minimum of ten and a maximum of fifty inflammatory papules and/or pustules in the facial area and * 10 to 100 comedones in the facial area * no more than 3 small nodules (approx. 5 mm in diameter) in the facial area * Male and female patients * Age greater or equal to 12 years * Ability and willingness to accept and comply with the administration of the investigational drugs over 12 weeks and to comply with the required medical examinations (signed informed consent). Exclusion Criteria: To be included in the study you MUST NOT have: * Localization of acne predominantly on the chest and/or the back or confined to the chest and/or the back * Sandpaper acne with hundreds of small facial comedones * Moderate or severe acne requiring systemic therapy * Multitude of small nodules and/or multiple large nodules, cysts, polyporous comedones, draining sinuses e.g. nodulocystic/conglobate acne * Other skin conditions that might interfere with acne diagnosis and/or evaluation (such as facial psoriasis, seborrheic dermatitis, perioral dermatitis and papulopustular rosacea) * Anticipated or scheduled hospitalization, e.g. for surgery, during the study * Female patients who have not continuously used their present brand of oral contraceptive (if any) or other hormone therapy for at least 3 months * Continuous concurrent use of any topical and/or systemic treatment which affects acne * History of hypersensitivity to any ingredient of the trial drugs * Concurrent involvement in another investigational study or participation within 30 days prior to the start of this study * You must not have taken or have had the following types of treatment or therapy prior to being admitted into the study: * Oral isotretinoin (i.e. Accutane) for 6 months * Ortho Tri-Cyclen or Estrostep for 3 months * Oral antibiotics (i.e. tetracyclines, erythromycin) for 4 weeks * Systemic corticosteroids for 4 weeks * Systemic non-steroidal anti-inflammatory drugs (NSAIDs) at anti-inflammatory doses for 4 weeks * Topical (applied to skin) retinoid creams, ointments, gels for 2 weeks * Topical antibiotics (i.e. tetracyclines, erythromycin, clindamycin) for 2 weeks * Topical corticosteroids or topical non-steroidal anti-inflammatory (NSAIDs) drugs for 2 weeks * Topical imidazole antimycotics for 2 weeks * Topical benzoyl peroxide (BPO) for 2 weeks * Topical over-the-counter remedies for acne (salicylic acid) for 2 weeks If you have had any of the above, you may still qualify for the study following a washout period (time for your body to completely eliminate, or get rid of, the medication). The study doctor will evaluate whether there is anything else in your history that may affect your safety in the study or interfere with evaluations. He/she may therefore advise you not to participate.