The therapeutic efficacy of a lotion containing 5% benzoyl peroxide and 2% miconazole was compared with 5% benzoyl peroxide alone, in a double-blind, randomized, parallel study. Thirty patients with comedonal or inflammatory acne vulgaris were enrolled. The medications were applied once daily during the first week, and then twice daily for the rest of the trial (45 days). In patients with comedonal acne there was no difference in the effect of the two therapies. In patients with inflammatory acne the percentage reduction of the number of lesions on Day 30 was significantly higher in the benzoyl peroxide plus miconazole group (66%) compared to benzoyl peroxide alone (37%). At Day 45 there was a trend favouring the combined therapy but the difference was not significant. There were no significant differences in the adverse reactions reported by the two groups of patients (erythema, itching or moderate exfoliation).