This study was carried out to investigate the inte actions between recipients and embryos to compare pregnancy rates in bovine embryo transfer, such as synchrony and stage of embryos, synchrony and quality of embryos, synchrony and side of uterine horn, and preservation time and stage of embryos. Fifty-two embryos were transferred by surgically to 42 Holstein heifers, 3 Holstein cows and 7 Korean native heifers from Feb., 1985 to June, 1986. The results were as follows: 1. In the trial of interactions between synchrony and embryo stage, recipients synchronired from- hours to + 12 hours in synchrony and embryos from morulac stage to advanced blastoctyst stages showed reason able pregnancy rate. 2. Excellant (A) and good (B) grade embryos showed good pregnancy rate, 81.8% and 73.3% respectively, but fair (C) grade embryos showed poor, 25% only at the same boundary of recipient synchrony. 3. More recipients had corpus luteum on the right ovary than the left, and also had better pregnancy rate (26/32 vs 13/20,81.3% vs 65%). 4. A good pregnancy rates (over 60%) were obtained with the embryo transferred 17hrs after flush at room temperature or field condition in culture medium.