Objective: To investigates the effect of mifepristone (anti-progesterone) on stromal cells of the uterus of rats. Study Design: Laboratory based randomized controlled trials Method: Sixty adult female rats were divided randomly into two groups, comprising of 30 animals in each group. In-group A 1ml of normal saline was given orally daily for three months while in group B mifepristone was given orally in a dose of 1mg/kg body weight daily for three months. All the animals were sacrificed next day after the last oral dose. 2ml blood was taken directly from the heart for measurement of progesterone levels. Sections were stained with hematoxylin and eosin for light microscopic study. Immunohistochemical staining procedure was done for demonstration of progesterone receptors Results: The stromal cells were flattened and irregular in outline present around the glands. Some appeared fusiform or spindle shaped. In the experimental group the stromal cells were tightly packed. There was an increase in the number of infiltration of granulocytes and eosinophils in the stroma. Progesterone antagonist application lowered the plasma concentration of progesterone. The number of progesterone receptors in all uterine compartments of the experimental group were decreased and found statistically significant. Conclusion: In conclusion, mifepristone affects stromal, glandular and epithelial morphology in the rat uterus.