Nine patients (8 girls and 1 boy) suffering from precocious puberty received daily 100 mg/m2 cyproterone acetate orally. This treatment inhibited the vaginal bleeding; breast-size and the axillary hair and pubic hair did not further increase. The height increment per year and the bone maturation slowed down. The urinary excretion of androgens was temporarily diminished. It is probable that the growth prognosis could be improved by the administration of cyproterone acetate.