A regimen for the safe and effective long-term treatment of acne vulgaris entails topically applying onto the affected skin area of a subject afflicted therewith, for a period of time of at least four (4) months, e.g., for at least twelve (12) months and advantageously on a daily basis and preferably once a day, a thus effective amount of a topical medicament containing adapalene and benzoyl peroxide, formulated into a pharmaceutically acceptable medium therefor.