Clomifene, also known as clomiphene, is a medication used to treat infertility in women who do not ovulate, including those with polycystic ovary syndrome. Use results in a greater chance of twins.It is taken by mouth once a day, with a course of treatment that usually lasts for 5 days.

Common side effects include pelvic pain and hot flashes. Other side effects can include changes in vision, vomiting, trouble sleeping, ovarian cancer, and seizures. It is not recommended in people with liver disease, abnormal vaginal bleeding of unknown cause, or who are pregnant. Clomifene is in the selective estrogen receptor modulator (SERM) family of medication and is a nonsteroidal medication. It works by causing the release of GnRH by the hypothalamus, and subsequently gonadotropin from the anterior pituitary.

Clomifene was approved for medical use in the United States in 1967. It is on the World Health Organization's List of Essential Medicines, under the category "Ovulation inducers" (Complementary List). Its introduction began the era of assisted reproductive technology.

Clomifene (particularly the purified enclomiphene isomer) has also been found to have a powerful ability to boost or restore testosterone levels in hypogonadal men.