Objective: To compare the mammographic change before and after conjugated equine estrogen (CEE) 0.625 mg/day in hysterectomized women. Design: A retrospective descriptive study. Setting: Menopause clinic, Maharaj Nakorn Chiang Mai Hospital. Material and Method: Dedicated mammograms and demographic data of 66 women who had been hysterectomized were reviewed. Post surgical menopausal women were recruited for the study. CEE 0.625 mg/day was given just after the operation. The baseline mammography was done before the initiation of HRT and they were compared with the follow-up mammography performed 12-18 months after therapy. The degree of increase in mammographic density was classified as follows: minimal changes (10-25% increased density), moderated change (26-50% increased density), and marked change (> 50% increased density). Results: The mean age ± SD was 47 ± 4.3 years old. The mean duration ± SD of hormone used was 13.5 ± 2.4 months. The most common indication for operation was myoma uteri (43.9%). On the baseline mammogram, 5 cases had cystic change and one case had a small circumscribed solid mass suspected to be fibroadenoma. On the follow-up mammograms, there were 2 cases (3.0%) detected to have significantly increased breast density. One was moderately increased and the other was markedly increased, but cystic changes and one fibroadenoma were not changed. Conclusion: CEE has little effect on increased mammographic density.