Utrogestan is a modern progesterone, which shows maximal effectiveness with minimal side effects. It is a natural progesterone in micronized form, which makes it suitable for oral administration and vaginal application with same effectiveness. The aim of our retrospective study was to evaluate the therapeutical effects of Utrogestan in women with threatened abortion in the first trimester. Our experience dated from about one year and a half. Sixty eight women were treated for threatened abortion with a daily dose of 400 mg Utrogestan. The treatment continued at least 14 days/average 21 days/. Utrogestan was administered orally twice daily. The main indications were first or consecutive threatened spontaneous abortion in first trimester. For the period of time no side effects and subjective complaints were established except particular cases of slight headache and dizziness after morning application. Sixty one of the sixty eight women were dehospitalised with healthy pregnancy with no side effects. In our experience we preferred to use the drug in women with lutein insufficiency before pregnancy. We conclude that Utrogestan can be widely applied in Obstetrics with the proper indications, such as threatened abortion in the first trimester. The prophylactic treatment in women with slighter complaints like dull pain and weight Utrogestan is applied one tablet twice daily. In graver cases the starting dosage is two tablets two or three times daily.