The aim of the present study was to evaluate different treatment schedules in some different types of acne using a quantitative counting technique. Systemic treatment with erythromycine 0.5 g daily and topical treatment with clindamycin phosphate solution 1% was found to be optimal from the efficacy/side effect ratio. The combined treatment was tried in heat-provoked and cosmetic acne with favourable results. Doubling of erythromycine dosage could not prevent premenstrual exacerbation of acne. Diazepam 4 mg daily for two weeks followed by an antihistamine in addition to erythromycine 0.5 g daily gave relatively good results in female patients with acne excorié. In acne coexisting with pronounced seborrhoic dermatitis of the face the addition of hydrocortisone cream 1% was of benefit, although Roaccutane may here be the drug of choice. In female postpubertal acne, the effect of cyproteronacetate-etynilestradiol (Diane) was not superior to treatment with erythromycine 0.5 g daily. By treating special subtypes differently, one could be able to improve the results of acne therapy.