We have given danazol to 25 women with mammary dysplasia. Clinical, cytologic and radiographic examinations were made before, during and after this treatment. In 23 patients breast pain disappeared completely. Danazol produced such a decrease in breast volume and density that on the mammogram the parenchyma was much more easily visualized. We suggest that danazol might be given before mammography to high risk women having dense dysplasic breasts, in order to ensure easier and more accurate interpretation.