Inhibition of lactation is now usually achieved by the use of dopaminergic or antiserotoninergic drugs. An interesting, alternative approach, however, is represented by the use of antiestrogenic agents, though their mechanism of action is still uncertain. We have given cyclofenil at daily doses of 1200, 800 and 600 mg to a total of 100 post-partum women who required not to lactate. The clinical results were excellent or good in 83 women, fair in 9 and poor in 8. After 3, 5, and 7 days of treatment serum prolactin levels of treated women, if compared with those of control group, showed a decrease ranging from 25 to 27%, from 42 to 44%, and from 60 to 64% respectively. Blood coagulation, as judged by several laboratory parameters, did not show abnormal changes in any subject treated with cyclofenil.