Introduction: Administering hCG induces ovulation at a me-dian of 36 hours  in 82-89% of mares . No difference was foundbetween buserelin and deslorelin , nor histrelin to hCG in theinterval to ovulation . Deslorelin (liquid vehicle) has equal effi-cacy to hCG and pelleted deslorelin in inducing ovulation [5, 6]. AnhCG/deslorelin combination is used in clinical practice, with onereportfinding no difference in ovulation rate between hCG;deslorelin; and the combination of hCG/deslorelin . This studycompared hCG/deslorelin combination to hCG, deslorelin and his-trelin and a placebo. The null hypotheses tested were: 1) There is nodifference in days to ovulation between“ovulating inducing drugs”and a placebo; and 2) There is no difference in days to ovulationbetween the hCG/deslorelin combination and hCG, deslorelin and histrelin.