Hormone replacement therapy has been used for decades to treat hormonal imbalances in women and more recently men. The purpose of this literature review was to evaluate different hormones used in this common practice and evaluate them for efficacy and safety. Research was conducted using PubMed and other databases from the Grand Valley State University Library. Keywords such as “hormone replacement therapy,” “estrogen risks,” and “hypogonadism” were used to evaluate peer-reviewed articles from 1993-2014. There is overwhelming evidence to suggest that testosterone seems to be an effective treatment for hypogonadism. Estrogen may also be effective if risk factors for breast cancer are taken into consideration. Hormone replacement therapy should utilize individual dosing and not be used long term until further research is conducted.