Using the ‘ground glass method’, the forehead seborrheic index of 72 patients was determined before and during local treatment with promestriene 1% in a o/w base. In hyperseborrheic patients a significant decrease of the seborrheic index was obtained from the 3rd week of treatment and maintained for all its duration, while in normoseborrheics no change was observed under the same conditions. It may be concluded that promestriene reduces the sebum secretion but only in hyperseborrheic patients.