Anastrazole, also known as anastrozole, is a drug indicated in the treatment of breast cancer in post-menopausal women.1 It is a new generation oral aromatase inhibitor, administered once a day. Since 1980, doctors have recommended taking tamoxifen to prevent breast cancer in women. However, recently, between February 2, 2003 and January 31, 2012, doctors conducted an experiment with 3864 post-menopausal women.2 The result was successful. Anastrazole reduced the risk of breast cancer in post-menopausal women. The experiment showed that anastrazole actually has fewer serious side effects than tamoxifen. After this experiment, anastrazole is used in therapies for the treatment and prevention of cancer. It is also used for women who have already taken tamoxifen before. Anastrazole is sold to people under the name Arimidex. Changes to the safety labeling of anastrazole were approved by the FDA's Center for Drug Evaluation and Research (CDER) in December 2008.3 Chemical figure from source3 Anastrazole is used to prevent breast cancer and this fact can be easily understood by looking at the chemistry of the drug. Anastrazole is considered an aromatase inhibitor. It inhibits the aromatase enzyme, which is responsible for converting androgens (produced by women in the adrenal glands) to estrogen.1 Anastrazole is not a steroid, but is considered a hormonal treatment. The IUPAC name of anastrazole (C17H19N5) is 2-[3-(2-cyanopropan-2-yl)-5-(1,2,4-triazol-1-ylmethyl) phenyl]-2-methylpropanenitrile.1 The wt. molecular weight of anastrazole is 293.36626 g/mol and the melting point is 130.14 °C. It is a form of white powder. The structure of the drug shows how it works in the human body. Anastrazole metabolism occurs primarily by N-dealkylation, hydroxylation, and glucuronidation at hormonal levels ina... middle of paper... and suppresses serum estradiol levels.8 After this process the man will acquire normal fertility and spermatogenesis. According to the study, regardless of whether the man is obese or not, the study still showed that anastrazole was effective in normalizing fertility. The aromatase enzyme converts testosterone to estradiol. Since anastrazole is an aromatase inhibitor, it suppresses the conversion of testosterone to estradiol. As estradiol decreases, testosterone levels increase and maintain normal testosterone. Off-label use of aromatase inhibitors to decrease peripheral conversion of testosterone to estradiol provides a unique method to manipulate normal regulatory mechanisms of the hypothalamic-pituitary-gonadal axis to promote endogenous normalization of testosterone levels and to improve spermatogenesis and fertility.8