This article reviews possibilities of artificial control of the oestro
us cycle in the horse. During the breeding season, oestrous can be ind
uced prematurely (PGF2alpha), oestrous can be delayed (gestagens) und
ovulation can be induced during oestrus (GnRH, hCG). In addition, diff
erent aproaches for the induction of ovulation during the anovulatory
phase in winter and during transition into the breeding season (light
regimes, GnRH, hCG) are discussed. Drugs approved for hormone therapy
in equine fertility practice in Germany are listed.