Progestogens appear to have a dual effect on the cell cycle in breast cells and breast cancer cells. There is initially stimulation of mitotic activity. However, continuous application leads to cell apoptosis. This depends on type, dose and length of progestogen application in relation to estrogen action. In benign breast disease the use of progestogens results not only in reduction of mastodynia, but also a reduction in breast gland size and disappearance of nodularity proven by clinical examination and follow-up including breast ultrasound.