Objective: To investigates the effect of mifepristone on height of the epithelial cells of the endometrium. Study Design: Laboratory based randomized controlled trials Place __ampersandsignamp; Duration of the study: Department of Anatomy, Army Medical College Rawalpindi from Jan. 2007-march 2007. Method: Sixty adult female rats were divided randomly into two groups, comprising of 30 animals in each group. In group A one ml of normal saline was given orally daily for three months while in group B mifepristone was given orally in a dose of 1 mg/kg body weight daily for three months. Results: In the experimental group reduction was observed in epithelial cell height. Significantly lower level of progesterone while higher level of estrogen level in experimental group was noted as compared to the control group. Conclusion: Long term mifepristone administration suppresses the endometrial proliferation and epithelium height was decreased. It also lowered the plasma concentration of progesterone. While the plasma concentration of the estrogen was raised