Clomifene
(E,Z)-2-(4-(2-chloro-1,2-diphenylethenyl)phenoxy)- N,N-diethyl-ethanamine
CAS number 911-45-5 or 50-41-9	ATC code G03GB02
Chemical formula	C26H28ClNO
Molecular weight	406 (without citrate) 598.10 (with citrate)
Bioavailability	High (>90%)
Metabolism	Hepatic (with enterohepatic circulation)
Elimination half life	5-7 days
Excretion	Mainly renal, some biliary
Pregnancy category	X (USA)
Legal status	N/A
Delivery	50 mg tablets

Clomifene or Clomifene citrate (old name clomiphene, sold as Clomid®, Serophene®, Milophene® and many others) is a selective estrogen receptor modulator (SERM), used mainly in female infertility due to anovulation (e.g. due to polycystic ovary syndrome). In some countries, it is also registered for use in men.

Clomifene is mixture of two geometric isomers, enclomifene and zuclomifene.

Clomifene acts by inhibiting the action of estrogen on the gonadotrope cells in the anterior pituitary gland. "Sensing" low estrogen levels, follicle-stimulating hormone release is increased, leading to a higher rate of ovulation and hence pregnancy.

Clomifene can lead to multiple ovulation, and hence increasing the risk of twins. In comparison to purified FSH, the rate of ovarian hyperstimulation syndrome is low. There may be an increased risk of ovarian cancer.