Abstract. Tubal sterilization can be performed by several surgical methods. It has often been reported that menstrual disorders appear after the operations, probably caused by hormonal disturbance. However, there is no published systematic study of the ovarian hormonal status after sterilization. In the present prospective study therefore, the plasma progesterone level has been determined during one menstrual cycle before and one after endotherm tubal laparoscopic coagulation. Plasma progesterone was chosen as normal levels of this hormone during the luteal phase reflect ovulation and an adequate corpus luteum. The endotherm coagulation method does not appear to cause any progesterone malfunction in the ovary.