The management of benign diseases of the breast aims to halt the progression of fibrocystic transformation and to eliminate the symptoms of pain and breast tenderness. Progestins can be used for this purpose. In a controlled, randomized, double-blind, parallel-group study we treated 31 women with mastopathy/mastodynia with the progestins medrogestone (10 mg/day) or dydrogesterone (10 mg/day) from day 14 to day 25 for six cycles. Before, during and at the end of therapy the following parameters were evaluated: subjective symptoms (pain, tenderness, impairment of daily activities), palpatory findings, sonographic diagnosis and sex hormone profiles. Cyclic administration of the low-dose progestins medrogestone and dydrogesterone proved to be an effective and safe treatment of mastodynia and mastopathy. The objective parameters palpatory findings and sonographic imaging of breast nodules and cysts improved in more than 50% of patients. Improvement was particularly marked in women with low progesterone levels in the second half of the cycle. After six treatment cycles, 75% of the patients treated with dydrogesterone and 86% of the patients treated with medrogestone were completely pain-free.