These studies were carried out to investigate the induction of superovulation, the synchroniration and the effect of the number of embryos transferred, the developmentai stage of embryos and the donor-recipient synchrony on pregnancy rate in cattle. The results obtained in these studies were as follows: 1. The number of oorpus leuteum(CL) and the embryos reoovered were higher in FSH treated animals than in PMSG treated (9.4 vs 8.1 and 6.1 vs 4.5) and showed the same trend in recovery rate (64.9% vs 55.6%). 2. Two shots of cioprostenol at 11 days showed significantly high no. of animals in estrus in order of crossbred, Holstein and Korean native cattle. No significant differencies were noted in the seoond shots groups. And the interval to estrus and response were shorter and better in second shot group than that in first shot group. 3. The pregnancy rate when additional one embryo was transferred after Al at estrus (52.8%) was higher than the group transferred one (32.8%) or two (36.9%) embryos. 4. The pregnancy rate of embryo in morula stage was better than that in blasto cyst stage (39.3% vs 32.5%). 5. The pregnancy rate in the recipients exhibited estrus later than the donor (66.7%) was the higher than those exhibited estrus (40.3%) or exhibited estrus before the donor (37.5%).