Birth control is of major importance in our country in order to reduce the rapidly expanding population and consequently its impact on the national income. IUDs as a method of birth control attained a worldwide acception especially in the presence of many reports that linked the admistration of contraceptive steroids with a higher incidence of serious systemic complications. There is controversy about the mechanism (s) of contraceptive action of IUDs and of the accompanied pain and increased menstrual bleeding. Furthermore, it is questionable that the presence of copper metal inside the uterine cavity may lead to peripheral and/or endometrial trace elements changes with IUDs use. The present study was performed to clarify the possible peripheral steroid hormones changes and peripheral and endometrial trace elements changes associated with the use of inert and copper- containing IUDs and to compare the findings with those of women not using any contraception. Eighty four females were the subjects of the present investigation. They were all healthy, regularly menstruating, of age group ( 18 - 35 Y. ), parity ( 4 to 6 ), non-lactating, free from any clinically apparent endocrinopathy or chronic diseases of the liver and biliary system, and not using any medications known to influence hormone hemostasis ( including hormonal contraceptives ). The subjects were devided into 3 groups; control group, copper T-200 users group and Lippes Loop users group. Each group was subclassified into females in the mid- follicular phase and others in the mid- luteal phase of the menstrual cycle. 149 From each participant 10 mls. venous blood sample and endometrial sample were collected. The sera separated were examined by radioimmunoassay techniques for estimation of progesterone, oestradiol, testosterone and cortisol and were examined by atomic absorption for trace elements levels determination. Endometrial samples were subjected for trace elements determination by atomic absorption.