Purpose: As many patients often showed the value of menopause although they were women of childbearing age, this study looked into their previous history. According to the findings, they were patients with a mastectomy due to breast cancer and were taking breast cancer treatment Tamoxifen (the women hormone inhibitor) after chemotherapy. This study is conducted to examine changes in FSH and E2 concentration of patients breast cancer patients of childbearing age according to Tamoxifen used to prevent recurrence of breast cancer and proliferation of mammary parenchyma. Materials and Methods: This study aims to investigate similarity in patients treated with surgery who were in their childbearing age and in values of FSH and E2 by dividing test results of FSH and E2 requested at the department of nuclear medicine among patients who visited this hospital from Jan. 2009 to Mar. 2010 into women of childbearing age (n=50), menopausal women (n=50), and patients with breast cancer surgery who take Tamoxifen (n=50) and then comparing the test results. Results: The FSH and E2 test results of 50 patients were compared and analyzed as average${pm}$standard deviation, and the results showed that the figure of women of childbearingage (n=50) was FSH : $7.14{pm}6.19$, E2 : $138.76{pm}85.40$, that of menopausal women (n=50) was FSH : $52.12{pm}24.43$, E2 : $15.06{pm}4.43$, and that of patients with breast cancer surgery who were in their childbearing age (n=50) was FSH : $44.21{pm}21.07$, E2 : $13.53{pm}4.26$. When these different results of FSH and E2 were compared, the value of patients with breast cancer surgery who were in their childbearing age with Tamoxifen was somewhat similar to that of menopausal women. Conclusion: The test results of FSH and E2 have reportedly found the test values of patients with breast cancer surgery could be similar to that of menopausal women eventhough they were in their childbearing age due to the women hormone inhibitor Tamoxifen. Therefore, if a tester conducts this experiment after understanding the clinical meaning, the reliability of the tester reporting test results would be increased.