bioidentical hormones Bioidentical Bioidentical hormone replacement therapy or hormone replacement therapy is a term that defines the use of hormones similar to a natural hormone in the treatment of hormone replacement therapy. In general, this therapy is used to replace the common hormones such as estrogen and testosterone, and is considered the type of alternative medicine. This therapy is used to reduce the chances of diseases such as osteoporosis, or to relieve patients suffering from symptoms of menopause.