Embryo transfer is now common in the equine breeding industry, but limited data are available evaluating pregnancy outcome. The objectives of this retrospective study were to 1) compare live foal rates in mares carrying their own pregnancy with live foal rates following embryo transfer and 2) evaluate the effect of mare age on pregnancy outcome. Medical records for mares bred during the years 2004-2006 to carry their own pregnancies or bred to donate an unfrozen embryo to a young (≤15 years old) recipient mare were analyzed. Mares were included if they were confirmed pregnant at 16 days after ovulation and pregnancy outcome data were available. Pregnancy outcome data were compared by Fisher’s exact test (2-tailed) and PROC GLIMMIX of SAS (SAS Institute Inc., Cary, NC, USA). A live healthy foal was born from 116 of 134 (86.6%) mares carrying their own foal and 144 of 171 (84.2%) embryo transfer recipients (P > 0.1). The live foal rate for "carry own" mares ≤15 years of age, 89/100 (89.0%), was not different (P > 0.1) from those >15 years of age, 27/34 (79.4%). Recipients of embryos from mares >15 years old had a live foal rate of 41/48 (85.4%), which was similar to the live foal rate of embryos from mares ≤15 years of age, 103/123 (83.7%) (P > 0.1). A significant linear trend (P < 0.05) for an increase in pregnancy loss with increased age was noted when data for both groups were combined (Table 1). In conclusion, no significant difference was noted in pregnancy outcome between embryo transfer recipients and mares carrying their own pregnancies.