Methylergometrine (other names include methylergonovine, methylergobasin, methergine, and d-lysergic acid 1-butanolamide) is a synthetic analogue of ergonovine, a psychedelic alkaloid found in ergot, and many species of morning glory. It is a member of the ergoline family and chemically similar to LSD, ergine, ergometrine, and lysergic acid. Due to its oxytocic properties, it has a medical use in obstetrics. According to Jonathan Ott, methylergonovine has LSD-like actions above 2 milligrams^{[citation needed]}. Clinical dosages are ten times lower.

Methylergometrine maleate is marketed under the trade name Methergine.

Methylergometrine is a blood vessel constrictor and smooth muscle agonist most commonly used to prevent or control excessive bleeding following childbirth and spontaneous or elective abortion. It also causes uterine contractions to aid in expulsion of retained products of conception after a missed abortion (miscarriage in which all or part of the fetus remains in the uterus) and to help deliver the placenta after childbirth. It is available as tablets or injection (IM or IV) or in liquid form to be taken orally.