A method for treating acne comprising applying once a day for up to 12 weeks to the skin of a patient in need thereof a surfactant-free, aqueous 2.5% w/w benzoyl peroxide gel that is suitable for topical application to the skin and that comprises water, a water-miscible organic solvent, 2.5% w/w benzoyl peroxide and 1.2% w/w clindamycin phosphate, and a suspension of benzoyl peroxide, the concentration (w/w) of the organic solvent being between one and four times the concentration (w/w) of the benzoyl peroxide, and the ratio of the water to the organic solvent being at least 12:1.