A six-year-old Standardbred maiden mare was referred to the Cornell Equine Park for a unilateral twin reduction on day 29 of gestation. Two heartbeat positive embryos of equal size were observed at the base of the left uterine horn. Due to the close proximity of the embryos and the fact that the owner chose not to breed the mare again in the same breeding season, it was elected to leave the embryos until day 40 of gestation in hope they would undergo natural reduction. However, both twins remained viable and transabdominal ultrasound-guided reduction was elected on day 90 of gestation. Two attempts at transabdominal ultrasound-guided reduction were performed 4 days apart, in which only one fetus was successfully reduced. At 125 days of gestation at a recheck appointment the remaining fetus was heartbeat negative, and the mare aborted both fetuses without complications. This senior seminar will review the most common scenarios of equine twinning, the importance of early pregnancy checks in the mare, the different techniques of reducing twin embryos, and the efficacy of each technique.