Methyltestosterone is a man-made form of testosterone, a naturally occurring sex hormone that is produced in a man's testicles. Small amounts of testosterone are also produced in a woman's ovaries and adrenal system. Methyltestosterone is used in men and boys to treat conditions caused by a lack of this hormone, such as delayed puberty or other hormonal imbalances. Methyltestosterone is also used in women to treat breast cancer that has spread to other parts of the body. Methyltestosterone may also be used for purposes not listed in this medication guide. Methitest is a synthetic form of testosterone, which is a sex hormone that is naturally found in men. The sex hormone is responsible for normal body functions in men such as growth of the genitals and teenagers inducing puberty. Methitest works as the natural occurring testosterone, and, therefore, it treats a lack of the hormone in men or boys. Methitest may be used in boys who have delayed puberty, erectile dysfunction, and breast cancer.